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Wu B, Liu Y, Li H, Zhu L, Zeng L, Zhang Z, Peng W. Liver as a new target organ in Alzheimer's disease: insight from cholesterol metabolism and its role in amyloid-beta clearance. Neural Regen Res 2025; 20:695-714. [PMID: 38886936 DOI: 10.4103/1673-5374.391305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 11/07/2023] [Indexed: 06/20/2024] Open
Abstract
Alzheimer's disease, the primary cause of dementia, is characterized by neuropathologies, such as amyloid plaques, synaptic and neuronal degeneration, and neurofibrillary tangles. Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs, targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment. Metabolic abnormalities are commonly observed in patients with Alzheimer's disease. The liver is the primary peripheral organ involved in amyloid-beta metabolism, playing a crucial role in the pathophysiology of Alzheimer's disease. Notably, impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease. In this review, we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism. Furthermore, we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.
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Affiliation(s)
- Beibei Wu
- Department of Integrated Traditional Chinese & Western Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Yuqing Liu
- Department of Integrated Traditional Chinese & Western Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Hongli Li
- Department of Integrated Traditional Chinese & Western Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Lemei Zhu
- Academician Workstation, Changsha Medical University, Changsha, Hunan Province, China
| | - Lingfeng Zeng
- Academician Workstation, Changsha Medical University, Changsha, Hunan Province, China
| | - Zhen Zhang
- Department of Integrated Traditional Chinese & Western Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- Yangsheng College of Traditional Chinese Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou Province, China
- Qinhuangdao Shanhaiguan Pharmaceutical Co., Ltd, Qinhuangdao, Hebei Province, China
| | - Weijun Peng
- Department of Integrated Traditional Chinese & Western Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
- National Clinical Research Center for Mental Disorder, The Second Xiangya Hospital, Central South University, Changsha, Hunan Province, China
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2
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Bánáti D, Hellman-Regen J, Mack I, Young HA, Benton D, Eggersdorfer M, Rohn S, Dulińska-Litewka J, Krężel W, Rühl R. Defining a vitamin A5/X specific deficiency - vitamin A5/X as a critical dietary factor for mental health. INT J VITAM NUTR RES 2024; 94:443-475. [PMID: 38904956 DOI: 10.1024/0300-9831/a000808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
A healthy and balanced diet is an important factor to assure a good functioning of the central and peripheral nervous system. Retinoid X receptor (RXR)-mediated signaling was identified as an important mechanism of transmitting major diet-dependent physiological and nutritional signaling such as the control of myelination and dopamine signalling. Recently, vitamin A5/X, mainly present in vegetables as provitamin A5/X, was identified as a new concept of a vitamin which functions as the nutritional precursor for enabling RXR-mediated signaling. The active form of vitamin A5/X, 9-cis-13,14-dehydroretinoic acid (9CDHRA), induces RXR-activation, thereby acting as the central switch for enabling various heterodimer-RXR-signaling cascades involving various partner heterodimers like the fatty acid and eicosanoid receptors/peroxisome proliferator-activated receptors (PPARs), the cholesterol receptors/liver X receptors (LXRs), the vitamin D receptor (VDR), and the vitamin A(1) receptors/retinoic acid receptors (RARs). Thus, nutritional supply of vitamin A5/X might be a general nutritional-dependent switch for enabling this large cascade of hormonal signaling pathways and thus appears important to guarantee an overall organism homeostasis. RXR-mediated signaling was shown to be dependent on vitamin A5/X with direct effects for beneficial physiological and neuro-protective functions mediated systemically or directly in the brain. In summary, through control of dopamine signaling, amyloid β-clearance, neuro-protection and neuro-inflammation, the vitamin A5/X - RXR - RAR - vitamin A(1)-signaling might be "one of" or even "the" critical factor(s) necessary for good mental health, healthy brain aging, as well as for preventing drug addiction and prevention of a large array of nervous system diseases. Likewise, vitamin A5/X - RXR - non-RAR-dependent signaling relevant for myelination/re-myelination and phagocytosis/brain cleanup will contribute to such regulations too. In this review we discuss the basic scientific background, logical connections and nutritional/pharmacological expert recommendations for the nervous system especially considering the ageing brain.
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Affiliation(s)
- Diána Bánáti
- Department of Food Engineering, Faculty of Engineering, University of Szeged, Hungary
| | - Julian Hellman-Regen
- Department of Psychiatry, Charité-Campus Benjamin Franklin, Section Neurobiology, University Medicine Berlin, Germany
| | - Isabelle Mack
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Germany
| | - Hayley A Young
- Faculty of Medicine, Health and Life Sciences, Swansea University, UK
| | - David Benton
- Faculty of Medicine, Health and Life Sciences, Swansea University, UK
| | - Manfred Eggersdorfer
- Department of Healthy Ageing, University Medical Center Groningen (UMCG), The Netherlands
| | - Sascha Rohn
- Department of Food Chemistry and Analysis, Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Germany
| | | | - Wojciech Krężel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, CNRS UMR 7104, Université de Strasbourg, Illkirch, France
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3
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Zhang R, Wuerch E, Yong VW, Xue M. LXR agonism for CNS diseases: promises and challenges. J Neuroinflammation 2024; 21:97. [PMID: 38627787 PMCID: PMC11022383 DOI: 10.1186/s12974-024-03056-0] [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: 01/09/2024] [Accepted: 02/27/2024] [Indexed: 04/19/2024] Open
Abstract
The unfavorable prognosis of many neurological conditions could be attributed to limited tissue regeneration in central nervous system (CNS) and overwhelming inflammation, while liver X receptor (LXR) may regulate both processes due to its pivotal role in cholesterol metabolism and inflammatory response, and thus receives increasing attentions from neuroscientists and clinicians. Here, we summarize the signal transduction of LXR pathway, discuss the therapeutic potentials of LXR agonists based on preclinical data using different disease models, and analyze the dilemma and possible resolutions for clinical translation to encourage further investigations of LXR related therapies in CNS disorders.
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Affiliation(s)
- Ruiyi Zhang
- Department of Cerebrovascular Diseases, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | - Emily Wuerch
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | - V Wee Yong
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.
| | - Mengzhou Xue
- Department of Cerebrovascular Diseases, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
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4
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Alnaaim SA, Al-Kuraishy HM, Alexiou A, Papadakis M, Saad HM, Batiha GES. Role of Brain Liver X Receptor in Parkinson's Disease: Hidden Treasure and Emerging Opportunities. Mol Neurobiol 2024; 61:341-357. [PMID: 37606719 PMCID: PMC10791998 DOI: 10.1007/s12035-023-03561-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 08/01/2023] [Indexed: 08/23/2023]
Abstract
Parkinson's disease (PD) is a neurodegenerative disease due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). The liver X receptor (LXR) is involved in different neurodegenerative diseases. Therefore, the objective of the present review was to clarify the possible role of LXR in PD neuropathology. LXRs are the most common nuclear receptors of transcription factors that regulate cholesterol metabolism and have pleiotropic effects, including anti-inflammatory effects and reducing intracellular cholesterol accumulation. LXRs are highly expressed in the adult brain and act as endogenous sensors for intracellular cholesterol. LXRs have neuroprotective effects against the development of neuroinflammation in different neurodegenerative diseases by inhibiting the expression of pro-inflammatory cytokines. LXRs play an essential role in mitigating PD neuropathology by reducing the expression of inflammatory signaling pathways, neuroinflammation, oxidative stress, mitochondrial dysfunction, and enhancement of BDNF signaling.In conclusion, LXRs, through regulating brain cholesterol homeostasis, may be effectual in PD. Also, inhibition of node-like receptor pyrin 3 (NLRP3) inflammasome and nuclear factor kappa B (NF-κB) by LXRs could effectively prevent neuroinflammation in PD. Taken together, LXRs play a crucial role in PD neuropathology by inhibiting neuroinflammation and associated degeneration of DNs.
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Affiliation(s)
- Saud A Alnaaim
- Clinical Neurosciences Department, College of Medicine, King Faisal University, Hofuf, Saudi Arabia
| | - Hayder M Al-Kuraishy
- Department of Clinical Pharmacology and Therapeutic Medicine, College of Medicine, ALmustansiriyiah University, Baghdad, 14132, Iraq
| | - Athanasios Alexiou
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham, NSW, 2770, Australia
- AFNP Med, 1030, Wien, Austria
| | - Marios Papadakis
- Department of Surgery II, University Hospital Witten-Herdecke, Heusnerstrasse 40, University of Witten-Herdecke, 42283, Wuppertal, Germany.
| | - Hebatallah M Saad
- Department of Pathology, Faculty of Veterinary Medicine, Matrouh University, Marsa Matruh, 51744, Egypt
| | - Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, AlBeheira, 22511, Egypt
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5
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Vacondio D, Nogueira Pinto H, Coenen L, Mulder IA, Fontijn R, van Het Hof B, Fung WK, Jongejan A, Kooij G, Zelcer N, Rozemuller AJ, de Vries HE, de Wit NM. Liver X receptor alpha ensures blood-brain barrier function by suppressing SNAI2. Cell Death Dis 2023; 14:781. [PMID: 38016947 PMCID: PMC10684660 DOI: 10.1038/s41419-023-06316-8] [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: 07/04/2023] [Revised: 11/09/2023] [Accepted: 11/15/2023] [Indexed: 11/30/2023]
Abstract
In Alzheimer's disease (AD) more than 50% of the patients are affected by capillary cerebral amyloid-angiopathy (capCAA), which is characterized by localized hypoxia, neuro-inflammation and loss of blood-brain barrier (BBB) function. Moreover, AD patients with or without capCAA display increased vessel number, indicating a reactivation of the angiogenic program. The molecular mechanism(s) responsible for BBB dysfunction and angiogenesis in capCAA is still unclear, preventing a full understanding of disease pathophysiology. The Liver X receptor (LXR) family, consisting of LXRα and LXRβ, was reported to inhibit angiogenesis and particularly LXRα was shown to secure BBB stability, suggesting a major role in vascular function. In this study, we unravel the regulatory mechanism exerted by LXRα to preserve BBB integrity in human brain endothelial cells (BECs) and investigate its role during pathological conditions. We report that LXRα ensures BECs identity via constitutive inhibition of the transcription factor SNAI2. Accordingly, deletion of brain endothelial LXRα is associated with impaired DLL4-NOTCH signalling, a critical signalling pathway involved in vessel sprouting. A similar response was observed when BECs were exposed to hypoxia, with concomitant LXRα decrease and SNAI2 increase. In support of our cell-based observations, we report a general increase in vascular SNAI2 in the occipital cortex of AD patients with and without capCAA. Importantly, SNAI2 strongly associated with vascular amyloid-beta deposition and angiopoietin-like 4, a marker for hypoxia. In hypoxic capCAA vessels, the expression of LXRα may decrease leading to an increased expression of SNAI2, and consequently BECs de-differentiation and sprouting. Our findings indicate that LXRα is essential for BECs identity, thereby securing BBB stability and preventing aberrant angiogenesis. These results uncover a novel molecular pathway essential for BBB identity and vascular homeostasis providing new insights on the vascular pathology affecting AD patients.
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Affiliation(s)
- D Vacondio
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - H Nogueira Pinto
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - L Coenen
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
- Biomedical Primate Research Centre, Department of Neurobiology and Aging, Rijswijk, the Netherlands
| | - I A Mulder
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
- Amsterdam UMC location University of Amsterdam, Department of Biomedical Engineering and Physics, Meibergdreef 9, Amsterdam, the Netherlands
| | - R Fontijn
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - B van Het Hof
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - W K Fung
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - A Jongejan
- Amsterdam UMC location University of Amsterdam, Epidemiology and Data Science, Meibergdreef 9, Amsterdam, The Netherlands
- Amsterdam Public Health, Methodology, Amsterdam, The Netherlands
- Amsterdam Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands
| | - G Kooij
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - N Zelcer
- Amsterdam UMC location University of Amsterdam Department of Medical Biochemistry, Meibergdreef 9, Amsterdam, the Netherlands
- Amsterdam UMC location University of Amsterdam, Cardiovascular Sciences and Gastroenterology and Metabolism, Meibergdreef 9, Amsterdam, the Netherlands
| | - A J Rozemuller
- Amsterdam Neuroscience, Amsterdam, the Netherlands
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Pathology, De Boelelaan 1117, Amsterdam, the Netherlands
| | - H E de Vries
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands
- Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - N M de Wit
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Molecular Cell Biology and Immunology, De Boelelaan 1108, Amsterdam, the Netherlands.
- Amsterdam Neuroscience, Amsterdam, the Netherlands.
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6
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Liver X Receptor Regulation of Glial Cell Functions in the CNS. Biomedicines 2022; 10:biomedicines10092165. [PMID: 36140266 PMCID: PMC9496004 DOI: 10.3390/biomedicines10092165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/19/2022] [Accepted: 08/29/2022] [Indexed: 11/22/2022] Open
Abstract
In this review, we discuss the role of liver X receptors (LXRs) in glial cells (microglia, oligodendrocytes and astrocytes) in the central nervous system (CNS). LXRs are oxysterol-activated nuclear receptors that, in adults, regulate genes involved in cholesterol homeostasis, the modulation of inflammatory responses and glutamate homeostasis. The study of LXR knockout mice has revealed that LXRβ plays a key role in maintaining the health of dopaminergic neurons in the substantia nigra, large motor neurons in the spinal cord and retinal ganglion cells in the eye. In the peripheral nervous system (PNS), LXRβ is responsible for the health of the spiral ganglion neurons (SGNs) in the cochlea. In addition, LXRs are essential for the homeostasis of the cerebrospinal fluid (CSF), and in LXRαβ−/− mice, the lateral ventricles are empty and lined with lipid-laden cells. As LXRαβ−/− mice age, lipid vacuoles accumulate in astrocytes surrounding blood vessels. By seven months of age, motor coordination becomes impaired, and there is a loss of motor neurons in the spinal cord of LXRβ−/− mice. During development, migration of neurons in the cortex and cerebellum is retarded in LXRβ−/− mice. Since LXRs are not expressed in dopaminergic or motor neurons in adult mice, the neuroprotective effects of LXRs appear to come from LXRs in glial cells where they are expressed. However, despite the numerous neurological deficits in LXR−/− rodents, multiple sclerosis has the clear distinction of being the only human neurodegenerative disease in which defective LXR signaling has been identified. In this review, we summarize the regulation and functions of LXRs in glial cells and analyze how targeting LXRs in glial cells might, in the future, be used to treat neurodegenerative diseases and, perhaps, disorders caused by aberrant neuronal migration during development.
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7
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Griffett K, Hayes M, Bedia-Diaz G, Appourchaux K, Sanders R, Boeckman MP, Koelblen T, Zhang J, Schulman IG, Elgendy B, Burris TP. Antihyperlipidemic Activity of Gut-Restricted LXR Inverse Agonists. ACS Chem Biol 2022; 17:1143-1154. [PMID: 35417135 DOI: 10.1021/acschembio.2c00057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hyperlipidemia and increased circulating cholesterol levels are associated with increased cardiovascular disease risk. The liver X receptors (LXRs) are regulators of de novo lipogenesis and cholesterol transport and have been validated as potential therapeutic targets for the treatment of atherosclerosis. However, efforts to develop LXR agonists to reduce cardiovascular diseases have failed due to poor clinical outcomes-associated increased hepatic lipogenesis and elevated low-density lipoprotein (LDL) cholesterol (C). Here, we report that LXR inverse agonists are effective in lowering plasma LDL cholesterol and triglycerides in several models of hyperlipidemia, including the Ldlr null mouse model of atherosclerosis. Mechanistic studies demonstrate that LXR directly regulates the expression of Soat2 enzyme in the intestine, which is directly responsible for the re-uptake or excretion of circulating lipids. Oral administration of a gut-specific LXR inverse agonist leads to reduction of Soat2 expression in the intestine and effectively lowers circulating LDL cholesterol and triglyceride levels without modulating LXR target genes in the periphery. In summary, our studies highlight the therapeutic potential of the gut-restricted molecules to treat hyperlipidemia and atherosclerosis through the intestinal LXR-Soat2 axis.
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Affiliation(s)
- Kristine Griffett
- Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama 36849, United States
| | - Matthew Hayes
- University of Florida Genetics Institute, Gainesville, Florida 32610, United States
| | - Gonzalo Bedia-Diaz
- Center for Clinical Pharmacology, Washington University School of Medicine and St. Louis College of Pharmacy, St. Louis, Missouri 63110, United States
| | - Kevin Appourchaux
- Center for Clinical Pharmacology, Washington University School of Medicine and St. Louis College of Pharmacy, St. Louis, Missouri 63110, United States
| | - Ryan Sanders
- University of Florida Genetics Institute, Gainesville, Florida 32610, United States
| | - Michael P. Boeckman
- Center for Clinical Pharmacology, Washington University School of Medicine and St. Louis College of Pharmacy, St. Louis, Missouri 63110, United States
| | - Thomas Koelblen
- University of Florida Genetics Institute, Gainesville, Florida 32610, United States
| | - Jinsong Zhang
- Department of Pharmacology & Physiology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - Ira G. Schulman
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22903, United States
| | - Bahaa Elgendy
- Center for Clinical Pharmacology, Washington University School of Medicine and St. Louis College of Pharmacy, St. Louis, Missouri 63110, United States
| | - Thomas P. Burris
- University of Florida Genetics Institute, Gainesville, Florida 32610, United States
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Shao F, Wang X, Wu H, Wu Q, Zhang J. Microglia and Neuroinflammation: Crucial Pathological Mechanisms in Traumatic Brain Injury-Induced Neurodegeneration. Front Aging Neurosci 2022; 14:825086. [PMID: 35401152 PMCID: PMC8990307 DOI: 10.3389/fnagi.2022.825086] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/21/2022] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the most common diseases in the central nervous system (CNS) with high mortality and morbidity. Patients with TBI usually suffer many sequelae in the life time post injury, including neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). However, the pathological mechanisms connecting these two processes have not yet been fully elucidated. It is important to further investigate the pathophysiological mechanisms underlying TBI and TBI-induced neurodegeneration, which will promote the development of precise treatment target for these notorious neurodegenerative consequences after TBI. A growing body of evidence shows that neuroinflammation is a pivotal pathological process underlying chronic neurodegeneration following TBI. Microglia, as the immune cells in the CNS, play crucial roles in neuroinflammation and many other CNS diseases. Of interest, microglial activation and functional alteration has been proposed as key mediators in the evolution of chronic neurodegenerative pathology following TBI. Here, we review the updated studies involving phenotypical and functional alterations of microglia in neurodegeneration after injury, survey key molecules regulating the activities and functional responses of microglia in TBI pathology, and explore their potential implications to chronic neurodegeneration after injury. The work will give us a comprehensive understanding of mechanisms driving TBI-related neurodegeneration and offer novel ideas of developing corresponding prevention and treatment strategies for this disease.
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Affiliation(s)
- Fangjie Shao
- Department of Plastic and Aesthetic Center, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaoyu Wang
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Haijian Wu
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Qun Wu
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- *Correspondence: Qun Wu,
| | - Jianmin Zhang
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Brain Research Institute, Zhejiang University, Hangzhou, China
- Collaborative Innovation Center for Brain Science, Zhejiang University, Hangzhou, China
- Jianmin Zhang,
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9
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Lewandowski CT, Laham MS, Thatcher GR. Remembering your A, B, C's: Alzheimer's disease and ABCA1. Acta Pharm Sin B 2022; 12:995-1018. [PMID: 35530134 PMCID: PMC9072248 DOI: 10.1016/j.apsb.2022.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/27/2021] [Accepted: 01/07/2022] [Indexed: 12/24/2022] Open
Abstract
The function of ATP binding cassette protein A1 (ABCA1) is central to cholesterol mobilization. Reduced ABCA1 expression or activity is implicated in Alzheimer's disease (AD) and other disorders. Therapeutic approaches to boost ABCA1 activity have yet to be translated successfully to the clinic. The risk factors for AD development and progression, including comorbid disorders such as type 2 diabetes and cardiovascular disease, highlight the intersection of cholesterol transport and inflammation. Upregulation of ABCA1 can positively impact APOE lipidation, insulin sensitivity, peripheral vascular and blood–brain barrier integrity, and anti-inflammatory signaling. Various strategies towards ABCA1-boosting compounds have been described, with a bias toward nuclear hormone receptor (NHR) agonists. These agonists display beneficial preclinical effects; however, important side effects have limited development. In particular, ligands that bind liver X receptor (LXR), the primary NHR that controls ABCA1 expression, have shown positive effects in AD mouse models; however, lipogenesis and unwanted increases in triglyceride production are often observed. The longstanding approach, focusing on LXRβ vs. LXRα selectivity, is over-simplistic and has failed. Novel approaches such as phenotypic screening may lead to small molecule NHR modulators that elevate ABCA1 function without inducing lipogenesis and are clinically translatable.
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10
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Yao S, Xu Z, Chen S, Meng Y, Xue Y, Yao W, Gao X. Silk fibroin hydrolysate improves memory impairment via multi-target function. J Funct Foods 2022. [DOI: 10.1016/j.jff.2022.104942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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11
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Chiang MC, Nicol CJB, Chen SJ, Huang RN. TO901317 activation of LXR-dependent pathways mitigate amyloid-beta peptide-induced neurotoxicity in 3D human neural stem cell culture scaffolds and AD mice. Brain Res Bull 2021; 178:57-68. [PMID: 34801648 DOI: 10.1016/j.brainresbull.2021.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 11/04/2021] [Accepted: 11/11/2021] [Indexed: 11/02/2022]
Abstract
Alzheimer's disease (AD) is the major cause of neurodegeneration worldwide and is characterized by the accumulation of amyloid beta (Aβ) in the brain, which is associated with neuronal loss and cognitive impairment. Liver X receptor (LXR), a critical nuclear receptor, and major regulator in lipid metabolism and inflammation, is suggested to play a protective role against the mitochondrial dysfunction noted in AD. In our study, our established 3D gelatin scaffold model and a well characterized in vivo (APP/PS1) murine model of AD were used to directly investigate the molecular, biochemical and behavioral effects of neuronal stem cell exposure to Aβ to improve understanding of the in vivo etiology of AD. Herein, human neural stem cells (hNSCs) in our 3D model were exposed to Aβ, and had significantly decreased cell viability, which correlated with decreased mRNA and protein expression of LXR, Bcl-2, CREB, PGC1α, NRF-1, and Tfam, and increased caspase 3 and 9 activities. Cotreatment with a synthetic agonist of LXR (TO901317) significantly abrogated these Aβ-mediated effects in hNSCs. Moreover, TO901317 cotreatment both significantly rescues hNSCs from Aβ-mediated decreases in ATP levels and mitochondrial mass, and significantly restores Aβ-induced fragmented mitochondria to almost normal morphology. TO901317 cotreatment also decreases tau aggregates in Aβ-treated hNSCs. Importantly, TO901317 treatment significantly alleviates the impairment of memory, decreases Aβ aggregates and increases proteasome activity in APP/PS1 mice; whereas, these effects were blocked by cotreatment with an LXR antagonist (GSK2033). Together, these novel results improve our mechanistic understanding of the central role of LXR in Aβ-mediated hNSC dysfunction. We also provide preclinical data unveiling the protective effects of using an LXR-dependent agonist, TO901317, to block the toxicity observed in Aβ-exposed hNSCs, which may guide future treatment strategies to slow or prevent neurodegeneration in some AD patients.
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Affiliation(s)
- Ming-Chang Chiang
- Department of Life Science, College of Science and Engineering, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Christopher J B Nicol
- Departments of Pathology & Molecular Medicine and Biomedical & Molecular Sciences, and Cancer Biology and Genetics Division, Cancer Research Institute, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Shiang-Jiuun Chen
- Department of Life Science and Institute of Ecology and Evolutionary Biology, College of Life Science, National Taiwan University, Taipei 106, Taiwan
| | - Rong-Nan Huang
- Department of Entomology and Research Center for Plant-Medicine, National Taiwan University, Taipei 106, Taiwan
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12
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Willems S, Zaienne D, Merk D. Targeting Nuclear Receptors in Neurodegeneration and Neuroinflammation. J Med Chem 2021; 64:9592-9638. [PMID: 34251209 DOI: 10.1021/acs.jmedchem.1c00186] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nuclear receptors, also known as ligand-activated transcription factors, regulate gene expression upon ligand signals and present as attractive therapeutic targets especially in chronic diseases. Despite the therapeutic relevance of some nuclear receptors in various pathologies, their potential in neurodegeneration and neuroinflammation is insufficiently established. This perspective gathers preclinical and clinical data for a potential role of individual nuclear receptors as future targets in Alzheimer's disease, Parkinson's disease, and multiple sclerosis, and concomitantly evaluates the level of medicinal chemistry targeting these proteins. Considerable evidence suggests the high promise of ligand-activated transcription factors to counteract neurodegenerative diseases with a particularly high potential of several orphan nuclear receptors. However, potent tools are lacking for orphan receptors, and limited central nervous system exposure or insufficient selectivity also compromises the suitability of well-studied nuclear receptor ligands for functional studies. Medicinal chemistry efforts are needed to develop dedicated high-quality tool compounds for the therapeutic validation of nuclear receptors in neurodegenerative pathologies.
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Affiliation(s)
- Sabine Willems
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
| | - Daniel Zaienne
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
| | - Daniel Merk
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
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13
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T0901317, an Agonist of Liver X Receptors, Attenuates Neuronal Apoptosis in Early Brain Injury after Subarachnoid Hemorrhage in Rats via Liver X Receptors/Interferon Regulatory Factor/P53 Upregulated Modulator of Apoptosis/Dynamin-1-Like Protein Pathway. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:8849131. [PMID: 34194609 PMCID: PMC8181056 DOI: 10.1155/2021/8849131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/29/2020] [Accepted: 05/12/2021] [Indexed: 12/28/2022]
Abstract
Methods Subarachnoid hemorrhage (SAH) models of Sprague-Dawley rats were established with perforation method. T0901317 was injected intraperitoneally 1-hour post-SAH. GSK2033, an inhibitor of LXRs, and interferon regulatory factor (IRF-1) CRISPR activation were injected intracerebroventricularly to evaluate potential signaling pathway. The severity of SAH, neurobehavior test in both short- and long-term and apoptosis was measured with Western blot and immunofluorescence staining. Results Expression of LXR-α and IRF-1 increased and peaked at 24 h post-SAH, while LXR-β remained unaffected in SAH+vehicle group compared with Sham group. Post-SAH T0901317 treatment attenuated neuronal impairments in both short- and long-term and decreased neuronal apoptosis, the expression of IRF-1, P53 upregulated modulator of apoptosis (PUMA), dynamin-1-like protein (Drp1), Bcl-2-associated X protein (Bax) and cleaved caspase-3, and increasing B-cell lymphoma 2 (Bcl-2) at 24 h from modeling. GSK2033 inhibited LXRs and reversed T0901317's neuroprotective effects. IRF-1 CRISPR activation upregulated the expression of IRF-1 and abolished the treatment effects of T0901317. Conclusion T0901317 attenuated neuronal apoptosis via LXRs/IRF-1/PUMA/Drp1 pathway in SAH rats.
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14
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Regulation of cytochrome P450 4F11 expression by liver X receptor alpha. Int Immunopharmacol 2020; 90:107240. [PMID: 33310663 DOI: 10.1016/j.intimp.2020.107240] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 11/20/2022]
Abstract
Cytochrome P450 4F (CYP4F) enzymes are responsible for the metabolism of eicosanoids, which play important roles in inflammation. Nuclear receptor liver X receptor alpha (LXRα) is a critical signal node connecting inflammation and lipid metabolism. Studies revealed that the release of cytokines and nuclear factor-κB (NF-κB) can change the CYP4F11 expression in HepG2 cells. However, the effect of LXRα on the CYP4F family and the underlying mechanism remain unclear. This study found that CYP4F11 is a target gene of LXRα. Luciferase assays and siRNA transfection showed that LXRα increased the transcription of CYP4F11 and LXRα agonist GW3965 could induce the expression of CYP4F11 by activating the LXRα-CYP4F11 pathway. Besides, overexpression of CYP4F11 could decrease TNF-α and IL-1β in lipopolysaccharide (LPS)-induced THP-1 cells. The finding of the regulation of CYP4F11 may contribute to the anti-inflammatory activity of LXRα agonists.
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15
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Cui W, Sun C, Ma Y, Wang S, Wang X, Zhang Y. Inhibition of TLR4 Induces M2 Microglial Polarization and Provides Neuroprotection via the NLRP3 Inflammasome in Alzheimer's Disease. Front Neurosci 2020; 14:444. [PMID: 32508567 PMCID: PMC7251077 DOI: 10.3389/fnins.2020.00444] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 04/09/2020] [Indexed: 11/18/2022] Open
Abstract
Accumulating evidence has indicated that activation of microglia and neuroinflammation reaction play a prominent role in Alzheimer’s disease (AD). Inhibition of toll-like receptor 4 (TLR4) has been shown to be associated with immune responses and brain damage, but its effects on AD remain unclear. This study mainly aimed to investigate the protective effect of TAK-242 (TLR4-specific inhibitor) on microglial polarization and neuroprotection in an AD mouse model and the underlying mechanisms. We found that APP/PS1 transgenic AD mice exhibited a dramatic increase in TLR4 levels concomitant with a significantly higher expression of inflammatory microglia compared to C57BL/6 wild-type mice. Furthermore, inhibition of TLR4 by TAK-242 administration significantly improved neurological function, decreased the level of Bax, and caused a significant reduction in the levels of M1-markers (iNOS and TNFα), while the expressions of M2-phenotype markers (Trem-2 and Arg-1) were increased both in vivo and in vitro. Furthermore, TAK-242 treatment enhanced BV2 microglial phagocytosis. Moreover, Aβ25–35 caused the upregulation of inflammatory cytokine production, MyD88, NF-kappaB-p65, and NLRP3, which could be ameliorated by NLRP3-siRNA or TAK-242. These findings indicated that TLR4 inhibition provided neuroprotection and promoted a microglial switch from the inflammatory M1 phenotype to the protective M2 phenotype in AD. The mechanism involved may be related to modulation of the MyD88/NF-kappaB/NLRP3 signaling pathway.
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Affiliation(s)
- Weigang Cui
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, China.,Xinxiang Key Laboratory of Molecular Neurology, Xinxiang Medical University, Xinxiang, China.,Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang Medical University, Xinxiang, China
| | - Chunli Sun
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, China.,Xinxiang Key Laboratory of Molecular Neurology, Xinxiang Medical University, Xinxiang, China
| | - Yuqi Ma
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, China
| | - Songtao Wang
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, China.,Xinxiang Key Laboratory of Molecular Neurology, Xinxiang Medical University, Xinxiang, China
| | - Xianwei Wang
- Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang Medical University, Xinxiang, China
| | - Yinghua Zhang
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, China.,Xinxiang Key Laboratory of Molecular Neurology, Xinxiang Medical University, Xinxiang, China
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16
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Cui W, Sun C, Ma Y, Wang S, Wang X, Zhang Y. Neuroprotective effect of tormentic acid against memory impairment and neuro‑inflammation in an Alzheimer's disease mouse model. Mol Med Rep 2020; 22:739-750. [PMID: 32468017 PMCID: PMC7339752 DOI: 10.3892/mmr.2020.11154] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 04/21/2020] [Indexed: 12/19/2022] Open
Abstract
Cognitive impairment and neuro-inflammatory responses are the distinctive characteristics of Alzheimer's disease (AD). Tormentic acid (TA) is one of the major active components of Potentilla chinensis and has been demonstrated to have anti-inflammatory properties. However, the potential effects of TA on neuro-inflammatory responses and memory impairment in AD remain unknown. The present study investigated the therapeutic effect of TA on neuro-inflammation, as well as learning and memory impairment in AD mice. In addition, the effects of TA treatment were also examined in a co-culture system of microglia and primary neurons. Intraperitoneal administration of TA attenuated memory deficits in amyloid β precursor protein/presenilin 1 transgenic mice, with a marked decrease in amyloid plaque deposition. TA also reduced microglial activation and decreased the secretion of pro-inflammatory factors in AD mice. Furthermore, pre-treatment with TA suppressed the production of pro-inflammatory markers, as well as the nuclear translocation of nuclear factor-κB (NF-κB) p65 induced by Aβ exposure in BV2 cells. TA also reduced inhibited neurotoxicity and improved neuron survival in a neuron-microglia co-culture system. Taken together, these findings suggested that TA could attenuate neuro-inflammation and memory impairment, which may be closely associated with regulation of the NF-κB pathway.
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Affiliation(s)
- Weigang Cui
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Chunli Sun
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Yuqi Ma
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Songtao Wang
- Xinxiang Key Laboratory of Molecular Neurology, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Xianwei Wang
- Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
| | - Yinghua Zhang
- Department of Human Anatomy, Xinxiang Medical University, Xinxiang, Henan 453003, P.R. China
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17
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Fitz NF, Nam KN, Koldamova R, Lefterov I. Therapeutic targeting of nuclear receptors, liver X and retinoid X receptors, for Alzheimer's disease. Br J Pharmacol 2019; 176:3599-3610. [PMID: 30924124 PMCID: PMC6715597 DOI: 10.1111/bph.14668] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/15/2019] [Accepted: 02/24/2019] [Indexed: 12/18/2022] Open
Abstract
After 15 years of research into Alzheimer's disease (AD) therapeutics, including billions of US dollars provided by federal agencies, pharmaceutical companies, and private foundations, there are still no meaningful therapies that can delay the onset or slow the progression of AD. An understanding of the proteolytic processing of amyloid precursor protein (APP) and the hypothesis that pathogenic mechanisms in familial and sporadic forms of AD are very similar led to the assumption that pharmacological inhibition of secretases or immunological approaches to clear amyloid depositions in the brain would have been the core to drug discovery strategies and successful therapies. However, there are other understudied approaches including targeting genes, gene networks, and metabolic pathways outside the proteolytic processing of APP. The advancement of newly developed sequencing technologies and mass spectrometry, as well as the availability of animal models expressing human apolipoprotein E isoforms, has been critical in rationalizing additional AD therapeutics. The purpose of this review is to present one of those approaches, based on the role of ligand-activated nuclear liver X and retinoid X receptors in the brain. This therapeutic approach was initially proposed utilizing in vitro models 15 years ago and has since been examined in numerous studies using AD-like mouse models. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.
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Affiliation(s)
- Nicholas F Fitz
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kyong Nyon Nam
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Radosveta Koldamova
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Iliya Lefterov
- Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
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18
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Mouzat K, Chudinova A, Polge A, Kantar J, Camu W, Raoul C, Lumbroso S. Regulation of Brain Cholesterol: What Role Do Liver X Receptors Play in Neurodegenerative Diseases? Int J Mol Sci 2019; 20:E3858. [PMID: 31398791 PMCID: PMC6720493 DOI: 10.3390/ijms20163858] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/06/2019] [Accepted: 08/06/2019] [Indexed: 12/11/2022] Open
Abstract
Liver X Receptors (LXR) alpha and beta are two members of nuclear receptor superfamily documented as endogenous cholesterol sensors. Following conversion of cholesterol in oxysterol, both LXR isoforms detect intracellular concentrations and act as transcription factors to promote expression of target genes. Among their numerous physiological roles, they act as central cholesterol-lowering factors. In the central nervous system (CNS), cholesterol has been shown to be an essential determinant of brain function, particularly as a major constituent of myelin and membranes. In the brain, LXRs act as cholesterol central regulators, and, beyond this metabolic function, LXRs have additional roles such as providing neuroprotective effects and lowering neuroinflammation. In many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and multiple sclerosis (MS), dysregulations of cholesterol and oxysterol have been reported. In this paper, we propose to focus on recent advances in the knowledge of the LXRs roles on brain cholesterol and oxysterol homeostasis, neuroinflammation, neuroprotection, and their putative involvement in neurodegenerative disorders. We will discuss their potential use as candidates for both molecular diagnosis and as promising pharmacological targets in the treatment of ALS, AD, or MS patients.
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Affiliation(s)
- Kevin Mouzat
- Motoneuron Disease: Pathophysiology and Therapy, The Neuroscience Institute of Montpellier, University of Montpellier, Montpellier, Laboratoire de Biochimie et Biologie Moléculaire, Nimes University Hospital, 30029 Nîmes, France.
| | - Aleksandra Chudinova
- Motoneuron Disease: Pathophysiology and Therapy, The Neuroscience Institute of Montpellier, University of Montpellier, Montpellier, Laboratoire de Biochimie et Biologie Moléculaire, Nimes University Hospital, 30029 Nîmes, France
| | - Anne Polge
- Laboratoire de Biochimie et Biologie Moléculaire, Nimes University Hospital, University of Montpellier, 30029 Nîmes, France
| | - Jovana Kantar
- Motoneuron Disease: Pathophysiology and Therapy, The Neuroscience Institute of Montpellier, University of Montpellier, Montpellier, Laboratoire de Biochimie et Biologie Moléculaire, Nimes University Hospital, 30029 Nîmes, France
| | - William Camu
- ALS Reference Center, Montpellier University Hospital and University of Montpellier, Inserm UMR1051, 34000 Montpellier, France
| | - Cédric Raoul
- The Neuroscience Institute of Montpellier, Inserm UMR1051, University of Montpellier, 34091 Montpellier, France
| | - Serge Lumbroso
- Motoneuron Disease: Pathophysiology and Therapy, The Neuroscience Institute of Montpellier, University of Montpellier, Montpellier, Laboratoire de Biochimie et Biologie Moléculaire, Nimes University Hospital, 30029 Nîmes, France
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19
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Wouters E, de Wit NM, Vanmol J, van der Pol SMA, van het Hof B, Sommer D, Loix M, Geerts D, Gustafsson JA, Steffensen KR, Vanmierlo T, Bogie JFJ, Hendriks JJA, de Vries HE. Liver X Receptor Alpha Is Important in Maintaining Blood-Brain Barrier Function. Front Immunol 2019; 10:1811. [PMID: 31417573 PMCID: PMC6685401 DOI: 10.3389/fimmu.2019.01811] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/17/2019] [Indexed: 12/17/2022] Open
Abstract
Dysfunction of the blood-brain barrier (BBB) contributes significantly to the pathogenesis of several neuroinflammatory diseases, including multiple sclerosis (MS). Potential players that regulate BBB function are the liver X receptors (LXRs), which are ligand activated transcription factors comprising two isoforms, LXRα, and LXRβ. However, the role of LXRα and LXRβ in regulating BBB (dys)function during neuroinflammation remains unclear, as well as their individual involvement. Therefore, the goal of the present study is to unravel whether LXR isoforms have different roles in regulating BBB function under neuroinflammatory conditions. We demonstrate that LXRα, and not LXRβ, is essential to maintain barrier integrity in vitro. Specific knockout of LXRα in brain endothelial cells resulted in a more permeable barrier with reduced expression of tight junctions. Additionally, the observed dysfunction was accompanied by increased endothelial inflammation, as detected by enhanced expression of vascular cell adhesion molecule (VCAM-1) and increased transendothelial migration of monocytes toward inflammatory stimuli. To unravel the importance of LXRα in BBB function in vivo, we made use of the experimental autoimmune encephalomyelitis (EAE) MS mouse model. Induction of EAE in a constitutive LXRα knockout mouse and in an endothelial specific LXRα knockout mouse resulted in a more severe disease score in these animals. This was accompanied by higher numbers of infiltrating leukocytes, increased endothelial VCAM-1 expression, and decreased expression of the tight junction molecule claudin-5. Together, this study reveals that LXRα is indispensable for maintaining BBB integrity and its immune quiescence. Targeting the LXRα isoform may help in the development of novel therapeutic strategies to prevent BBB dysfunction, and thereby neuroinflammatory disorders.
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Affiliation(s)
- Elien Wouters
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Nienke M. de Wit
- Department of Molecular Cell Biology and Immunology, Amsterdam Neuroscience, MS Center Amsterdam, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Jasmine Vanmol
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Susanne M. A. van der Pol
- Department of Molecular Cell Biology and Immunology, Amsterdam Neuroscience, MS Center Amsterdam, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Bert van het Hof
- Department of Molecular Cell Biology and Immunology, Amsterdam Neuroscience, MS Center Amsterdam, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Daniela Sommer
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Melanie Loix
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Dirk Geerts
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Jan Ake Gustafsson
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Knut R. Steffensen
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Tim Vanmierlo
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
- Division Translational Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Jeroen F. J. Bogie
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Jerome J. A. Hendriks
- School of Life Sciences, Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Helga E. de Vries
- Department of Molecular Cell Biology and Immunology, Amsterdam Neuroscience, MS Center Amsterdam, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
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20
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Li P, Wang G, Zhang XL, He GL, Luo X, Yang J, Luo Z, Shen TT, Yang XS. MicroRNA-155 Promotes Heat Stress-Induced Inflammation via Targeting Liver X Receptor α in Microglia. Front Cell Neurosci 2019; 13:12. [PMID: 30778287 PMCID: PMC6369214 DOI: 10.3389/fncel.2019.00012] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 01/14/2019] [Indexed: 12/12/2022] Open
Abstract
Background: The neuroinflammatory responses of microglial cells play an important role in the process of brain dysfunction caused by heat stroke. MicroRNAs are reportedly involved in a complex signaling network and have been identified as neuroinflammatory regulators. In this study, we determined the biological roles of microRNA-155 in the inflammatory responses in heat-stressed microglia and explored the underlying mechanisms. Methods: MicroRNA-155 mimic and inhibitor were used to separately upregulate or downregulate microRNA-155 expression. The activation state of BV-2 microglial cells (BV-2 cells) was assessed via immunoreactions using the microglial marker CD11b and CD68. Levels of induced interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured using real-time reverse transcription polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assays (ELISAs). The activation of nuclear factor kappa B (NF-κB) signaling proteins was evaluated by Western blotting for inhibitory kappa B alpha (IκBα) and NF-κB p65 phosphorylation and indirect immunofluorescence analysis using a p65 phosphorylation antibody. A luciferase reporter assay was used to verify liver X receptor α (LXRα) as a target gene of microRNA-155. Results: Heat stress significantly induced IL-1β, IL-6, and TNF-α release and increased the expression of CD11b and CD68. In addition, IκBα and NF-κB p65 phosphorylation were dramatically increased by heat stress, and microRNA-155 expression was also elevated. High expression of microRNA-155 in heat-stressed microglial cells was inversely correlated with LXRα expression. We then determined the role of microRNA-155 in the heat stress-induced inflammatory responses. The results revealed that by targeting LXRα, microRNA-155 enhanced NF-κB signaling activation and facilitated immune inflammation in heat stress-treated BV-2 cells. Conclusion: MicroRNA-155 promotes heat stress-induced inflammatory responses in microglia. The underlying mechanisms may include facilitating inflammatory factors expression by increasing NF-κB pathway activation via targeting LXRα.
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Affiliation(s)
- Ping Li
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Gong Wang
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China.,Department of Neurology, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Xiao-Liang Zhang
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China.,Department of Cardiology, Kunming General Hospital of Chengdu Military Command, Yunnan, China
| | - Gen-Lin He
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Xue Luo
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Ju Yang
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Zhen Luo
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Ting-Ting Shen
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
| | - Xue-Sen Yang
- Laboratory of Extreme Environmental Medicine, Department of Tropical Medicine, Army Medical University, Chongqing, China
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21
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Mohan S, Koller EJ, Fazal JA, De Oliveria G, Pawlowicz AI, Doré S. Genetic Deletion of PGF 2α-FP Receptor Exacerbates Brain Injury Following Experimental Intracerebral Hemorrhage. Front Neurosci 2018; 12:556. [PMID: 30233287 PMCID: PMC6134069 DOI: 10.3389/fnins.2018.00556] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 07/23/2018] [Indexed: 01/17/2023] Open
Abstract
Background: The release of inflammatory molecules such as prostaglandins (e.g., PGF2α) is associated with brain damage following an intracerebral hemorrhagic (ICH) stroke; however, the role of PGF2α and its cognate FP receptor in ICH remains unclear. This study focused on investigating the role of the FP receptor as a target for novel neuroprotective drugs in a preclinical model of ICH, aiming to investigate the contribution of the PGF2α-FP axis in modulating functional recovery and anatomical outcomes following ICH. Results: Neurological deficit scores in FP−/− mice were significantly higher compared to WT mice 72 h after ICH (6.1 ± 0.7 vs. 3.1 ± 0.8; P < 0.05). Assessing motor skills, the total time mice stayed on the rotating rod was significantly less in FP−/−mice compared to WT mice 24 h after ICH (27.0 ± 7.5 vs. 52.4 ± 11.2 s; P < 0.05). Using grip strength to quantify forepaw strength, results showed that the FP−/− mice had significantly less strength compared to WT mice 72 h after ICH (96.4 ± 17.0 vs. 129.6 ± 5.9 g; P < 0.01). In addition to the behavioral outcomes, histopathological measurements were made. In Cresyl violet stained brain sections, the FP−/− mice showed a significantly larger lesion volume compared to the WT (15.0 ± 2.2 vs. 3.2 ± 1.7 mm3; P < 0.05 mice.) To estimate the presence of ferric iron in the peri-hematoma area, Perls' staining was performed, which revealed that FP−/− mice had significantly greater staining than the WT mice (186.3 ± 34.4% vs. 86.9 ± 13.0% total positive pixel counts, P < 0.05). Immunoreactivity experiments on brain sections from FP−/− and WT mice post-ICH were performed to monitor changes in microgliosis and astrogliosis using antibodies against Iba1 and GFAP respectively. These experiments showed that FP−/− mice had a trend toward greater astrogliosis than WT mice post-ICH. Conclusion: We showed that deletion of the PGF2α FP receptor exacerbates behavioral impairments and increases lesion volumes following ICH compared to WT-matched controls.Detailed mechanisms responsible for these novel results are actively being pursued.
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Affiliation(s)
- Shekher Mohan
- Department of Pharmaceutical Sciences, Manchester University, College of Pharmacy, Natural and Health Sciences, Fort Wayne, IN, United States
| | - Emily J Koller
- Department of Anesthesiology, University of Florida, College of Medicine, Gainesville, FL, United States
| | - Jawad A Fazal
- Department of Anesthesiology, University of Florida, College of Medicine, Gainesville, FL, United States
| | - Gabriela De Oliveria
- Department of Anesthesiology, University of Florida, College of Medicine, Gainesville, FL, United States
| | - Anna I Pawlowicz
- Department of Anesthesiology, University of Florida, College of Medicine, Gainesville, FL, United States
| | - Sylvain Doré
- Department of Anesthesiology, University of Florida, College of Medicine, Gainesville, FL, United States.,Departments of Neurology, Psychiatry, Psychology, Pharmaceutics and Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, College of Medicine, Gainesville, FL, United States
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22
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de Wit NM, Vanmol J, Kamermans A, Hendriks JJA, de Vries HE. Inflammation at the blood-brain barrier: The role of liver X receptors. Neurobiol Dis 2017; 107:57-65. [DOI: 10.1016/j.nbd.2016.09.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 09/11/2016] [Accepted: 09/17/2016] [Indexed: 02/05/2023] Open
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23
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Liver X Receptor α Is Involved in Counteracting Mechanical Allodynia by Inhibiting Neuroinflammation in the Spinal Dorsal Horn. Anesthesiology 2017; 127:534-547. [PMID: 28617705 DOI: 10.1097/aln.0000000000001718] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Liver X receptors, including α and β isoforms, are ligand-activated transcription factors. Whether liver X receptor α plays a role in neuropathic pain is unknown. METHODS A spared nerve injury model was established in adult male rats and mice. Von Frey tests were performed to evaluate the neuropathic pain behavior; Western blot and immunohistochemistry were performed to understand the underlying mechanisms. RESULTS Intrathecal injection of a specific liver X receptor agonist T0901317 or GW3965 could either prevent the development of mechanical allodynia or alleviate the established mechanical allodynia, both in rats and wild-type mice. GW3965 could inhibit the activation of glial cells and the expression of tumor necrosis factor-α (mean ± SD: 196 ± 48 vs. 119 ± 57; n = 6; P < 0.01) and interleukin 1β (mean ± SD: 215 ± 69 vs. 158 ± 74; n = 6; P < 0.01) and increase the expression of interleukin 10 in the spinal dorsal horn. All of the above effects of GW3965 could be abolished by liver X receptor α mutation. Moreover, more glial cells were activated, and more interleukin 1β was released in the spinal dorsal horn in liver X receptor α knockout mice than in wild-type mice after spared nerve injury. Aminoglutethimide, a neurosteroid synthesis inhibitor, blocked the inhibitory effect of T0901317 on mechanical allodynia, on the activation of glial cells, and on the expression of cytokines. CONCLUSIONS Activation of liver X receptor α inhibits mechanical allodynia by inhibiting the activation of glial cells and rebalancing cytokines in the spinal dorsal horn via neurosteroids.
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Holtman IR, Skola D, Glass CK. Transcriptional control of microglia phenotypes in health and disease. J Clin Invest 2017; 127:3220-3229. [PMID: 28758903 DOI: 10.1172/jci90604] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Microglia are the main resident macrophage population of the CNS and perform numerous functions required for CNS development, homeostasis, immunity, and repair. Many lines of evidence also indicate that dysregulation of microglia contributes to the pathogenesis of neurodegenerative and behavioral diseases. These observations provide a compelling argument to more clearly define the mechanisms that control microglia identity and function in health and disease. In this Review, we present a conceptual framework for how different classes of transcription factors interact to select and activate regulatory elements that control microglia development and their responses to internal and external signals. We then describe functions of specific transcription factors in normal and pathological contexts and conclude with a consideration of open questions to be addressed in the future.
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Affiliation(s)
- Inge R Holtman
- Department of Cellular and Molecular Medicine, UCSD, San Diego, California, USA.,Department of Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Dylan Skola
- Department of Cellular and Molecular Medicine, UCSD, San Diego, California, USA
| | - Christopher K Glass
- Department of Cellular and Molecular Medicine, UCSD, San Diego, California, USA.,Department of Medicine, UCSD, San Diego, California, USA
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25
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Fessler MB. The challenges and promise of targeting the Liver X Receptors for treatment of inflammatory disease. Pharmacol Ther 2017; 181:1-12. [PMID: 28720427 DOI: 10.1016/j.pharmthera.2017.07.010] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The Liver X Receptors (LXRs) are oxysterol-activated transcription factors that upregulate a suite of genes that together promote coordinated mobilization of excess cholesterol from cells and from the body. The LXRs, like other nuclear receptors, are anti-inflammatory, inhibiting signal-dependent induction of pro-inflammatory genes by nuclear factor-κB, activating protein-1, and other transcription factors. Synthetic LXR agonists have been shown to ameliorate atherosclerosis and a wide range of inflammatory disorders in preclinical animal models. Although this has suggested potential for application to human disease, systemic LXR activation is complicated by hepatic steatosis and hypertriglyceridemia, consequences of lipogenic gene induction in the liver by LXRα. The past several years have seen the development of multiple advanced LXR therapeutics aiming to avoid hepatic lipogenesis, including LXRβ-selective agonists, tissue-selective agonists, and transrepression-selective agonists. Although several synthetic LXR agonists have made it to phase I clinical trials, none have progressed due to unforeseen adverse reactions or undisclosed reasons. Nonetheless, several sophisticated pharmacologic strategies, including structure-guided drug design, cell-specific drug targeting, as well as non-systemic drug routes have been initiated and remain to be comprehensively explored. In addition, recent studies have identified potential utility for targeting the LXRs during therapy with other agents, such as glucocorticoids and rexinoids. Despite the pitfalls encountered to date in translation of LXR agonists to human disease, it appears likely that this accelerating field will ultimately yield effective and safe applications for LXR targeting in humans.
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Affiliation(s)
- Michael B Fessler
- National Institute of Environmental Health Sciences, 111 T.W. Alexander Drive, P.O. Box 12233, MD D2-01, Research Triangle Park, NC 27709, United States.
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26
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Dai B, Lei C, Lin R, Tao L, Bin Y, Peng H, Lei B. Activation of liver X receptor α protects amyloid β 1-40 induced inflammatory and senescent responses in human retinal pigment epithelial cells. Inflamm Res 2017; 66:523-534. [PMID: 28361293 DOI: 10.1007/s00011-017-1036-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 03/09/2017] [Accepted: 03/13/2017] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE To investigate whether activation of the liver X receptors (LXRs) inhibits amyloid β1-40 (Aβ1-40) induced inflammatory and senescent responses in human retinal pigment epithelial (RPE) cells. MATERIALS AND METHODS Confluent cultures of human primary RPE and ARPE-19 cells pretreated with 5 μΜ of TO901317 (TO90), a synthetic agonist of LXR, or vehicle were incubated with 1 μΜ of Aβ1-40 or Aβ40-1. The optimum concentrations of Aβ1-40 and TO90 were determined by cell viability assay. Pro-inflammatory cytokines IL-6, IL-8, MCP-1 were detected by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Expression and localization of an aging protein p16INK4a (p16) were analyzed by western blotting and immunofluorescence. Expressions of LXRs and one of their target genes ATP-binding cassette transporter A1 (ABCA1) were examined by real-time PCR and western blotting. Phosphorylated transcription inhibition factor-κB-α (p-IκB-α) was assessed by western blotting. RESULTS A negative linear relationship between the Aβ1-40 concentration and the cell viability was evident, indicating Aβ1-40 decreased ARPE-19 cell viability in a dose-dependent manner. Aβ1-40 enhanced the expression of IL-6, IL-8, MCP-1 as well as p16 in both RPE cell lines at both mRNA and protein levels, whereas TO90 counteracted the detrimental effects. TO90 upregulated the expression of LXRα and its target gene ABCA1, but it did not affect the expression of LXRβ. Meanwhile, TO90 inhibited the phosphorylation of IκB-α mediated by Aβ1-40 stimulation. CONCLUSION Activation of the LXRα-ABCA1 axis may alleviate Aβ1-40 induced inflammatory and senescent responses in RPE cells. The beneficial effect appears associated with the inhibition of the NF-κB signaling pathway.
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Affiliation(s)
- Bingling Dai
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China
| | - Chunyan Lei
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China
| | - Ru Lin
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China
| | - Lifei Tao
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China
| | - Yue Bin
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China
| | - Hui Peng
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China.
| | - Bo Lei
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, China.
- Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, 7 Weiwu Road, Zhengzhou, 450003, China.
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27
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Moutinho M, Landreth GE. Therapeutic potential of nuclear receptor agonists in Alzheimer's disease. J Lipid Res 2017; 58:1937-1949. [PMID: 28264880 DOI: 10.1194/jlr.r075556] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/03/2017] [Indexed: 11/20/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by an extensive accumulation of amyloid-β (Aβ) peptide, which triggers a set of deleterious processes, including synaptic dysfunction, inflammation, and neuronal injury, leading to neuronal loss and cognitive impairment. A large body of evidence supports that nuclear receptor (NR) activation could be a promising therapeutic approach for AD. NRs are ligand-activated transcription factors that regulate gene expression and have cell type-specific effects. In this review, we discuss the mechanisms that underlie the beneficial effects of NRs in AD. Moreover, we summarize studies reported in the last 10-15 years and their major outcomes arising from the pharmacological targeting of NRs in AD animal models. The dissection of the pathways regulated by NRs in the context of AD is of importance in identifying novel and effective therapeutic strategies.
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Affiliation(s)
- Miguel Moutinho
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106 and Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Gary E Landreth
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106 and Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202
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Wang JZ, Fang Y, Ji WD, Xu H. LXR agonists promote the proliferation of neural progenitor cells through MEK-ERK pathway. Biochem Biophys Res Commun 2016; 483:216-222. [PMID: 28034754 DOI: 10.1016/j.bbrc.2016.12.163] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 12/23/2016] [Indexed: 11/18/2022]
Abstract
The liver X receptors (LXRs) are transcriptional regulators of lipid homeostasis and may be critical for neurodegeneration and neurogenesis in vivo. However, it remains largely unknown about the role of LXRs and its agonists in the in vitro proliferation of neural progenitor cells (NPCs). Here we revealed for the first time that LXRs were markedly expressed in mouse NPCs and were critical for the in vitro proliferation. LXR agonists GW3965 and LXR623 promoted the proliferation of wildtype NPCs, but not NPCs from LXR double-knockout mice. Mechanistically, phosphorylation of MEK1/2 and ERK1/2 in NPCs was enhanced upon LXR agonist treatment, while abrogation of MEK/ERK phosphorylation by the inhibitors PD98059 and U0126 impaired the proliferation of wildtype NPCs in the presence or absence of LXR agonists. Collectively, our findings suggest that LXR agonists GW3965 and LXR623 can stimulate the NPC proliferation in LXR- and MEK/ERK-dependent manner.
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Affiliation(s)
- Jing-Zhong Wang
- Department of Neurology, The First People's Hospital of Shangqiu City, No 292, South Kaixuan Rd., Shangqiu 476100, Henan, People's Republic of China.
| | - Yan Fang
- Department of Neurology, The First People's Hospital of Shangqiu City, No 292, South Kaixuan Rd., Shangqiu 476100, Henan, People's Republic of China
| | - Wei-Dong Ji
- Department of Neurology, The First People's Hospital of Shangqiu City, No 292, South Kaixuan Rd., Shangqiu 476100, Henan, People's Republic of China
| | - Hui Xu
- Department of Neurology, The First People's Hospital of Shangqiu City, No 292, South Kaixuan Rd., Shangqiu 476100, Henan, People's Republic of China
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29
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Courtney R, Landreth GE. LXR Regulation of Brain Cholesterol: From Development to Disease. Trends Endocrinol Metab 2016; 27:404-414. [PMID: 27113081 PMCID: PMC4986614 DOI: 10.1016/j.tem.2016.03.018] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 03/31/2016] [Accepted: 03/31/2016] [Indexed: 01/07/2023]
Abstract
Liver X receptors (LXRs) are master regulators of cholesterol homeostasis and inflammation in the central nervous system (CNS). The brain, which contains a disproportionately large amount of the body's total cholesterol (∼25%), requires a complex and delicately balanced cholesterol metabolism to maintain neuronal function. Dysregulation of cholesterol metabolism has been implicated in numerous neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Due to their cholesterol-sensing and anti-inflammatory activities, LXRs are positioned centrally in the everyday maintenance of CNS function. This review focuses on recent research into the role of LXRs in the CNS during normal development and homeostasis and in disease states.
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Affiliation(s)
- Rebecca Courtney
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Gary E Landreth
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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30
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Wu CH, Chen CC, Lai CY, Hung TH, Lin CC, Chao M, Chen SF. Treatment with TO901317, a synthetic liver X receptor agonist, reduces brain damage and attenuates neuroinflammation in experimental intracerebral hemorrhage. J Neuroinflammation 2016; 13:62. [PMID: 26968836 PMCID: PMC4788882 DOI: 10.1186/s12974-016-0524-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 03/03/2016] [Indexed: 11/10/2022] Open
Abstract
Background Intracerebral hemorrhage (ICH) induces a series of inflammatory processes that contribute to neuronal damage and neurological deterioration. Liver X receptors (LXRs) are nuclear receptors that negatively regulate transcriptional processes involved in inflammatory responses, but their role in the pathology following ICH remains unclear. The present study investigated the neuroprotective effects and anti-inflammatory actions of TO901317, a synthetic LXR agonist, in a model of collagenase-induced ICH and in microglial cultures. Methods Mice subjected to collagenase-induced ICH injury were injected with either TO901317 (30 mg/kg) or vehicle 10 min after ICH and subsequently daily for 2 days. Behavioral studies, histology analysis, and assessments of hematoma volumes, brain water content, and blood-brain barrier (BBB) permeability were performed. The protein expression of LXR-α, LXR-β, ATP binding cassette transporter-1 (ABCA-1), and inflammatory molecules was analyzed. The anti-inflammatory mechanism of TO901317 was investigated in cultured microglia that were stimulated with either lipopolysaccharide (LPS) or thrombin. Results ICH induced an increase in LXR-α protein levels in the hemorrhagic hemisphere at 6 h whereas LXR-β expression remained unaffected. Both LXR-α and LXR-β were expressed in neurons and microglia in the peri-ICH region and but rarely in astrocytes. TO901317 significantly attenuated functional deficits and brain damage up to 28 days post-ICH. TO901317 also reduced neuronal death, BBB disruption, and brain edema at day 4 post-ICH. These changes were associated with marked reductions in microglial activation, neutrophil infiltration, and expression levels of inflammatory mediators at 4 and 7 days. However, TO901317 had no effect on matrix metalloproteinase-9 activity. In BV2 microglial cultures, TO901317 attenuated LPS- and thrombin-stimulated nitric oxide production and reduced LPS-induced p38, JNK, MAPK, and nuclear factor-kappa B (NF-κB) signaling. Moreover, delaying administration of TO901317 to 3 h post-ICH reduced brain tissue damage and neuronal death. Conclusions Our results suggest that enhancing LXR activation may provide a potential therapy for ICH by modulating the cytotoxic functions of microglia. Electronic supplementary material The online version of this article (doi:10.1186/s12974-016-0524-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chun-Hu Wu
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, Republic of China.,Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Chien-Cheng Chen
- Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, Taiwan, Republic of China
| | - Chai-You Lai
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, Republic of China.,Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Tai-Ho Hung
- Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital at Taipei and College of Medicine, Chang Gung University, Taipei, Taiwan, Republic of China
| | - Chao-Chang Lin
- Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, Taiwan, Republic of China
| | - Min Chao
- School of Medicine, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Szu-Fu Chen
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, Republic of China. .,Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, Taiwan, Republic of China.
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31
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Skerrett R, Pellegrino MP, Casali BT, Taraboanta L, Landreth GE. Combined Liver X Receptor/Peroxisome Proliferator-activated Receptor γ Agonist Treatment Reduces Amyloid β Levels and Improves Behavior in Amyloid Precursor Protein/Presenilin 1 Mice. J Biol Chem 2015; 290:21591-602. [PMID: 26163517 DOI: 10.1074/jbc.m115.652008] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 12/12/2022] Open
Abstract
Alzheimer disease (AD) is characterized by the extracellular accumulation of amyloid β (Aβ), which is accompanied by a robust inflammatory response in the brain. Both of these pathogenic processes are regulated by nuclear receptors, including the liver X receptors (LXRs) and peroxisome-proliferator receptor γ (PPARγ). Agonists of LXRs have been demonstrated previously to reduce Aβ levels and improve cognitive deficits in AD mouse models by inducing the transcription and lipidation of apolipoprotein E (apoE). Agonists targeting PPARγ reduce the microglial expression of proinflammatory genes and have also been shown to modulate apoE expression. Here we investigate whether a combination therapy with both LXR and PPARγ agonists results in increased benefits in an AD mouse model. We found that the LXR agonist GW3965 and the PPARγ agonist pioglitazone were individually able to increase the levels of apoE and related genes, decrease the expression of proinflammatory genes, and facilitate Aβ decreases in the hippocampus. Combined treatment with both agonists provoked a further increase in the expression of apoE and a decrease in the soluble and deposited forms of Aβ. The decrease in plaques was associated with increased colocalization between microglia and plaques. In addition, the PPARγ agonist in the combined treatment paradigm was able to counteract the elevation in plasma triglycerides that is a side effect of LXR agonist treatment. These results suggest that combined LXR/PPARγ agonist treatment merits further investigation for the treatment of AD.
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Affiliation(s)
- Rebecca Skerrett
- From the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106 and
| | - Mateus P Pellegrino
- the School of Medicine, University of Campinas, Campinas, Sao Paulo 13083-887, Brazil
| | - Brad T Casali
- From the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106 and
| | - Laura Taraboanta
- From the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106 and
| | - Gary E Landreth
- From the Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106 and
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32
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Liver X receptors alpha and beta promote myelination and remyelination in the cerebellum. Proc Natl Acad Sci U S A 2015; 112:7587-92. [PMID: 26023184 DOI: 10.1073/pnas.1424951112] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The identification of new pathways governing myelination provides innovative avenues for remyelination. Liver X receptors (LXRs) α and β are nuclear receptors activated by oxysterols that originated from the oxidation of cholesterol. They are crucial for cholesterol homeostasis, a major lipid constituent of myelin sheaths that are formed by oligodendrocytes. However, the role of LXRs in myelin generation and maintenance is poorly understood. Here, we show that LXRs are involved in myelination and remyelination processes. LXRs and their ligands are present in oligodendrocytes. We found that mice invalidated for LXRs exhibit altered motor coordination and spatial learning, thinner myelin sheaths, and reduced myelin gene expression. Conversely, activation of LXRs by either 25-hydroxycholesterol or synthetic TO901317 stimulates myelin gene expression at the promoter, mRNA, and protein levels, directly implicating LXRα/β in the transcriptional control of myelin gene expression. Interestingly, activation of LXRs also promotes oligodendroglial cell maturation and remyelination after lysolecithin-induced demyelination of organotypic cerebellar slice cultures. Together, our findings represent a conceptual advance in the transcriptional control of myelin gene expression and strongly support a new role of LXRs as positive modulators in central (re)myelination processes.
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Theofilopoulos S, Arenas E. Liver X receptors and cholesterol metabolism: role in ventral midbrain development and neurodegeneration. F1000PRIME REPORTS 2015; 7:37. [PMID: 26097711 PMCID: PMC4447034 DOI: 10.12703/p7-37] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of the ventral midbrain is orchestrated by a number of cell-extrinsic and -intrinsic factors that control critical processes, such as the patterning of the neural tube along the main body axis and the specification of diverse neuronal cell types in distinct positions of the neural tube. Subsequently, the regulation of neurogenesis and survival— acquire particular relevance in order to define the final size of diverse neuronal populations. In a series of studies during the last few years, we have identified liver X receptors (LXRs) as critical regulators of ventral midbrain development. Moreover, specific cholesterol derivatives present in the midbrain or in the cerebrospinal fluid were identified as LXR ligands, capable of specifically and selectively regulating neurogenesis and the survival of distinct neuronal populations, including midbrain dopamine neurons. These studies have shown that cholesterol derivatives are an entirely new class of factors capable of regulating both neuronal survival and neurogenesis, thus providing a direct link between cholesterol metabolism and brain development. In addition, LXRs and cholesterol metabolism were found to play a critical role in regulating the balance between neuronal survival and death in diverse midbrain neuronal populations. In this review, we will focus on these two aspects and on the possible role of cholesterol metabolism and LXRs in neurodegeneration.
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34
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Skerrett R, Malm T, Landreth G. Nuclear receptors in neurodegenerative diseases. Neurobiol Dis 2014; 72 Pt A:104-16. [PMID: 24874548 PMCID: PMC4246019 DOI: 10.1016/j.nbd.2014.05.019] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/14/2014] [Accepted: 05/17/2014] [Indexed: 01/04/2023] Open
Abstract
Nuclear receptors have generated substantial interest in the past decade as potential therapeutic targets for the treatment of neurodegenerative disorders. Despite years of effort, effective treatments for progressive neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease and ALS remain elusive, making non-classical drug targets such as nuclear receptors an attractive alternative. A substantial literature in mouse models of disease and several clinical trials have investigated the role of nuclear receptors in various neurodegenerative disorders, most prominently AD. These studies have met with mixed results, yet the majority of studies in mouse models report positive outcomes. The mechanisms by which nuclear receptor agonists affect disease pathology remain unclear. Deciphering the complex signaling underlying nuclear receptor action in neurodegenerative diseases is essential for understanding this variability in preclinical studies, and for the successful translation of nuclear receptor agonists into clinical therapies.
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Affiliation(s)
- Rebecca Skerrett
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
| | - Tarja Malm
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA; A.I. Virtanen Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Neulaniementie 2, 70211 Kuopio, Finland.
| | - Gary Landreth
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
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35
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Cudaback E, Yang Y, Montine TJ, Keene CD. APOE genotype-dependent modulation of astrocyte chemokine CCL3 production. Glia 2014; 63:51-65. [PMID: 25092803 DOI: 10.1002/glia.22732] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 07/14/2014] [Indexed: 12/19/2022]
Abstract
Apolipoprotein E (apoE) is well known as a regulator of cholesterol homeostasis, and is increasingly recognized to play a prominent role in the modulation of innate immune response, including cell-to-cell communication and migration. Alzheimer's disease (AD) is a slowly progressive neurodegenerative disorder characterized by neuroinflammation that appears to be an important component of the pathophysiology of the disease. Astrocytes are the majority cell type in brain, exerting significant influence over a range of central nervous system activities, including microglial-mediated neuroinflammatory responses. As the resident innate immune effector cells of the brain, microglia respond to soluble chemical signals released from tissue during injury and disease by mobilizing to lesion sites, clearing toxic molecules, and releasing chemical signals of their own. While microglial-mediated neuroinflammation in the AD brain remains an area of intense investigation, the mechanisms underlying reinforcement and regulation of these aberrant microglial responses by astrocytes are largely unstudied. Moreover, although inheritance of APOE ɛ4 represents the greatest genetic risk factor for sporadic AD, the mechanism by which apoE isoforms differentially influence AD pathophysiology is unknown. Here we show that APOE ɛ4 genotype specifically modulates astrocyte secretion of potent microglial chemotactic agents, including CCL3, thus providing evidence that APOE modulation of central nervous system (CNS) innate immune response is mediated through astrocytes.
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Affiliation(s)
- Eiron Cudaback
- Department of Pathology, University of Washington, Seattle, Washington
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36
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Fu Y, Tian Y, Wei Z, Liu H, Song X, Liu W, Zhang W, Wang W, Cao Y, Zhang N. Liver X receptor agonist prevents LPS-induced mastitis in mice. Int Immunopharmacol 2014; 22:379-83. [PMID: 25066757 DOI: 10.1016/j.intimp.2014.07.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 01/26/2023]
Abstract
Liver X receptor-α (LXR-α) which belongs to the nuclear receptor superfamily, is a ligand-activated transcription factor. Best known for its ability to regulate lipid metabolism and transport, LXRs have recently also been implicated in regulation of inflammatory response. The aim of this study was to investigate the preventive effects of synthetic LXR-α agonist T0901317 on LPS-induced mastitis in mice. The mouse model of mastitis was induced by injection of LPS through the duct of mammary gland. T0901317 was injected 1h before and 12h after induction of LPS intraperitoneally. The results showed that T0901317 significantly attenuated the infiltration of neutrophilic granulocytes, and the activation of myeloperoxidase (MPO); down-regulated the level of pro-inflammatory mediators including TNF-α, IL-1β, IL-6, COX-2 and PEG2; inhibited the phosphorylation of IκB-α and NF-κB p65, caused by LPS. Moreover, we report for the first time that LXR-α activation impaired LPS-induced mastitis. Taken together, these data indicated that T0901317 had protective effect on mastitis and the anti-inflammatory mechanism of T0901317 on LPS induced mastitis in mice may be due to its ability to inhibit NF-κB signaling pathway. LXR-α activation can be used as a therapeutic approach to treat mastitis.
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Affiliation(s)
- Yunhe Fu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Yuan Tian
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Zhengkai Wei
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Hui Liu
- Daqing Honggang District Animal Health Supervision, Daqing, Heilongjiang Province 163000, PR China
| | - Xiaojing Song
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Wenbo Liu
- Daqing Honggang District Animal Health Supervision, Daqing, Heilongjiang Province 163000, PR China
| | - Wenlong Zhang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Wei Wang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Yongguo Cao
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China
| | - Naisheng Zhang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, PR China.
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Sodhi RK, Singh N. Liver X receptor agonist T0901317 reduces neuropathological changes and improves memory in mouse models of experimental dementia. Eur J Pharmacol 2014; 732:50-9. [DOI: 10.1016/j.ejphar.2014.03.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 03/13/2014] [Accepted: 03/20/2014] [Indexed: 01/08/2023]
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Abstract
The vast majority of Alzheimer's disease (AD) cases are late onset (LOAD), which is genetically complex with heritability estimates up to 80%. Apolipoprotein E (APOE) has been irrefutably recognized as the major genetic risk factor, with semidominant inheritance, for LOAD. Although the mechanisms that underlie the pathogenic nature of APOE in AD are still not completely understood, emerging data suggest that APOE contributes to AD pathogenesis through both amyloid-β (Aβ)-dependent and Aβ-independent pathways. Given the central role for APOE in the modulation of AD pathogenesis, many therapeutic strategies have emerged, including converting APOE conformation, regulating APOE expression, mimicking APOE peptides, blocking the APOE/Aβ interaction, modulating APOE lipidation state, and gene therapy. Accumulating evidence also suggests the utility of APOE genotyping in AD diagnosis, risk assessment, prevention, and treatment response.
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Affiliation(s)
- Jin-Tai Yu
- Department of Neurology, Qingdao Municipal Hospital, School of Medicine, Qingdao University, Qingdao 266071, China; ,
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Regulation of prostaglandin F2α against β amyloid clearance and its inflammation induction through LXR/RXR heterodimer antagonism in microglia. Prostaglandins Other Lipid Mediat 2013; 106:45-52. [DOI: 10.1016/j.prostaglandins.2013.09.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 09/04/2013] [Accepted: 09/17/2013] [Indexed: 12/13/2022]
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Steffensen KR, Jakobsson T, Gustafsson JÅ. Targeting liver X receptors in inflammation. Expert Opin Ther Targets 2013; 17:977-90. [PMID: 23738533 DOI: 10.1517/14728222.2013.806490] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION The two oxysterol receptors, 'liver X receptors (LXRs)' LXRα and LXRβ, are amongst the emerging newer drug targets within the nuclear receptor family and targeting LXRs represents novel strategies needed for prevention and treatment of diseases where current therapeutics is inadequate. AREAS COVERED This review discusses the current understanding of LXR biology with an emphasis on the molecular aspects of LXR signalling establishing their potential as drug targets. Recent advances of their transcriptional mechanisms in inflammatory pathways and their physiological roles in inflammation and immunity are described. EXPERT OPINION The new discoveries of LXR-regulated inflammatory pathways have ignited new promises for LXRs as drug targets. The broad physiological roles of LXRs involve a high risk of unwanted side effects. Recent insights into LXR biology of the brain indicate a highly important role in neuronal development and a clinical trial testing an LXR agonist reported adverse neurological side effects. This suggests that drug development must focus on limiting the range of LXR signalling - possibly achieved through subtype, tissue specific, promoter specific or pathway specific activation of LXRs where a successful candidate drug must be carefully studied for its effect in the central nervous system.
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Affiliation(s)
- Knut R Steffensen
- Karolinska Institutet, Center for Biosciences, Department of Biosciences and Nutrition, S-14183 Stockholm, Sweden.
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Cermenati G, Brioschi E, Abbiati F, Melcangi RC, Caruso D, Mitro N. Liver X receptors, nervous system, and lipid metabolism. J Endocrinol Invest 2013; 36:435-43. [PMID: 23609963 DOI: 10.3275/8941] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Lipids in the nervous system are represented by cholesterol and phospholipids as constituents of cell membranes and, in particular, of myelin. Therefore, lipids are finely regulated to guarantee physiological functions. In the central nervous system, cholesterol is locally synthesized due to the presence of the blood brain barrier. In the peripheral nervous system cholesterol is either up-taken by lipoproteins and/or produced by de novo biosynthesis. Defects in lipid homeostasis in these tissues lead to structural and functional changes that often result in different pathological conditions depending on the affected pathways (i.e. cholesterol biosynthesis, cholesterol efflux, fatty acid biosynthesis etc.). Alterations in cholesterol metabolism in the central nervous system are linked to several disorders such as Alzheimer's disease, Huntington disease, Parkinson disease, Multiple sclerosis, Smith-Lemli-Opitz syndrome, Niemann-Pick type C disease, and glioblastoma. In the peripheral nervous system changes in lipid metabolism are associated with the development of peripheral neuropathy that may be caused by metabolic disorders, injuries, therapeutics, and autoimmune diseases. Transcription factors, such as the Liver X receptors (LXR), regulate both cholesterol and fatty acid metabolism in several tissues including the nervous system. In the last few years several studies elucidated the biology of LXR in the nervous system due to the availability of knock-out mice and the development of synthetic ligands. Here, we review a survey of the literature focused on the central and peripheral nervous system and in physiological and pathological settings with particular attention to the roles played by LXR in both districts.
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Affiliation(s)
- G Cermenati
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, Milan, Italy
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Xu P, Li D, Tang X, Bao X, Huang J, Tang Y, Yang Y, Xu H, Fan X. LXR Agonists: New Potential Therapeutic Drug for Neurodegenerative Diseases. Mol Neurobiol 2013; 48:715-28. [DOI: 10.1007/s12035-013-8461-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 04/09/2013] [Indexed: 01/04/2023]
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Abstract
A number of widespread and devastating chronic diseases, including atherosclerosis, type 2 diabetes, and Alzheimer's disease, have a pathophysiologically important inflammatory component. In these diseases, the precise identity of the inflammatory stimulus is often unknown and, if known, is difficult to remove. Thus, there is interest in therapeutically targeting the inflammatory response. Although there has been success with anti-inflammatory therapy in chronic diseases triggered by primary inflammation dysregulation or autoimmunity, there are considerable limitations. In particular, the inflammatory response is critical for survival. As a result, redundancy, compensatory pathways, and necessity narrow the risk:benefit ratio of anti-inflammatory drugs. However, new advances in understanding inflammatory signaling and its links to resolution pathways, together with new drug development, offer promise in this area of translational biomedical research.
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Affiliation(s)
- Ira Tabas
- Department of Medicine, Department of Anatomy and Cell Biology, and Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Christopher K. Glass
- Department of Cellular and Molecular Medicine and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0651, USA
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Pathogenesis, modulation, and therapy of Alzheimer’s disease: A perspective on roles of liver-X receptors. Transl Neurosci 2013. [DOI: 10.2478/s13380-013-0136-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
AbstractThe pathogenesis of Alzheimer’s disease (AD) has been mostly linked to aberrant amyloid beta (Aβ) and tau proteins metabolism, disturbed lipid/cholesterol homeostasis, and progressive neuroinflammation. Liver X receptors (LXR) are ligand-activated transcription factors, best known as the key regulators of cholesterol metabolism and transport. In addition, LXR signaling has been shown to have significant anti-inflammatory properties. In this brief review, we focus on the outcome of studies implicating LXR in the pathogenesis, modulation, and therapy of AD.
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