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Nam Y, Ji YJ, Shin SJ, Park HH, Yeon SH, Kim SY, Son RH, Jang GY, Kim HD, Moon M. Platycodon grandiflorum root extract inhibits Aβ deposition by breaking the vicious circle linking oxidative stress and neuroinflammation in Alzheimer's disease. Biomed Pharmacother 2024; 177:117090. [PMID: 38968796 DOI: 10.1016/j.biopha.2024.117090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/27/2024] [Accepted: 07/01/2024] [Indexed: 07/07/2024] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease accompanied by irreversible cognitive impairment. A deleterious feedback loop between oxidative stress and neuroinflammation in early AD exacerbates AD-related pathology. Platycodon grandiflorum root extract (PGE) has antioxidant and anti-inflammatory effects in several organs. However, the mechanisms underlying the effects of PGE in the brain remain unclear, particularly regarding its impact on oxidative/inflammatory damage and Aβ deposition. Thus, we aim to identify the mechanism through which PGE inhibits Aβ deposition and oxidative stress in the brain by conducting biochemical and histological analyses. First, to explore the antioxidant mechanism of PGE in the brain, we induced oxidative stress in mice injected with scopolamine and investigated the effect of PGE on cognitive decline and oxidative damage. We also assessed the effect of PGE on reactive oxygen species (ROS) generation and the expressions of antioxidant enzymes and neurotrophic factor in H2O2- and Aβ-treated HT22 hippocampal cells. Next, we investigated whether PGE, which showed antioxidant effects, could reduce Aβ deposition by mitigating neuroinflammation, especially microglial phagocytosis. We directly verified the effect of PGE on microglial phagocytosis, microglial activation markers, and pro-inflammatory cytokines in Aβ-treated BV2 microglial cells. Moreover, we examined the effect of PGE on neuroinflammation, inducing microglial responses in Aβ-overexpressing 5XFAD transgenic mice. PGE exerts antioxidant effects in the brain, enhances microglial phagocytosis of Aβ, and inhibits neuroinflammation and Aβ deposition, ultimately preventing neuronal cell death in AD. Taken together, our findings indicate that the therapeutic potential of PGE in AD is mediated by its targeting of multiple pathological processes.
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Affiliation(s)
- Yunkwon Nam
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Republic of Korea
| | - Yun-Jeong Ji
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science (NIHHS), Eumsung 27709, Republic of Korea
| | - Soo Jung Shin
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Republic of Korea
| | - Hyun Ha Park
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Republic of Korea
| | - Sung-Hum Yeon
- Healthcare Research Division, HuonsGlobal Bldg., A-dong Pangyo I-Square, 17, Changeop-ro, Sujeong-gu, Seongnam-si, Gyeonggi-do 13449, Republic of Korea
| | - Sang-Yoon Kim
- Healthcare Research Division, HuonsGlobal Bldg., A-dong Pangyo I-Square, 17, Changeop-ro, Sujeong-gu, Seongnam-si, Gyeonggi-do 13449, Republic of Korea
| | - Rak Ho Son
- Healthcare Research Division, HuonsGlobal Bldg., A-dong Pangyo I-Square, 17, Changeop-ro, Sujeong-gu, Seongnam-si, Gyeonggi-do 13449, Republic of Korea
| | - Gwi Yeong Jang
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science (NIHHS), Eumsung 27709, Republic of Korea
| | - Hyung Don Kim
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science (NIHHS), Eumsung 27709, Republic of Korea; Department of Biochemistry, School of Life Sciences, Chungbuk National University, Cheongju 28644, Republic of Korea.
| | - Minho Moon
- Department of Biochemistry, College of Medicine, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Republic of Korea; Research Institute for Dementia Science, Konyang University, 158, Gwanjeodong-ro, Seo-gu, Daejeon 35365, Republic of Korea.
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DeMarino C, Cowen M, Williams A, Khatkar P, Abulwerdi FA, Henderson L, Denniss J, Pleet ML, Luttrell DR, Vaisman I, Liotta LA, Steiner J, Le Grice SFJ, Nath A, Kashanchi F. Autophagy Deregulation in HIV-1-Infected Cells Increases Extracellular Vesicle Release and Contributes to TLR3 Activation. Viruses 2024; 16:643. [PMID: 38675983 PMCID: PMC11054313 DOI: 10.3390/v16040643] [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: 10/31/2023] [Revised: 04/12/2024] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection can result in HIV-associated neurocognitive disorder (HAND), a spectrum of disorders characterized by neurological impairment and chronic inflammation. Combined antiretroviral therapy (cART) has elicited a marked reduction in the number of individuals diagnosed with HAND. However, there is continual, low-level viral transcription due to the lack of a transcription inhibitor in cART regimens, which results in the accumulation of viral products within infected cells. To alleviate stress, infected cells can release accumulated products, such as TAR RNA, in extracellular vesicles (EVs), which can contribute to pathogenesis in neighboring cells. Here, we demonstrate that cART can contribute to autophagy deregulation in infected cells and increased EV release. The impact of EVs released from HIV-1 infected myeloid cells was found to contribute to CNS pathogenesis, potentially through EV-mediated TLR3 (Toll-like receptor 3) activation, suggesting the need for therapeutics to target this mechanism. Three HIV-1 TAR-binding compounds, 103FA, 111FA, and Ral HCl, were identified that recognize TAR RNA and reduce TLR activation. These data indicate that packaging of viral products into EVs, potentially exacerbated by antiretroviral therapeutics, may induce chronic inflammation of the CNS observed in cART-treated patients, and novel therapeutic strategies may be exploited to mitigate morbidity.
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Affiliation(s)
- Catherine DeMarino
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Discovery Hall Room 182, 10900 University Blvd., Manassas, VA 20110, USA; (C.D.); (M.C.); (A.W.); (P.K.); (M.L.P.)
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (L.H.); (J.D.); (D.R.L.); (A.N.)
| | - Maria Cowen
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Discovery Hall Room 182, 10900 University Blvd., Manassas, VA 20110, USA; (C.D.); (M.C.); (A.W.); (P.K.); (M.L.P.)
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (L.H.); (J.D.); (D.R.L.); (A.N.)
| | - Anastasia Williams
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Discovery Hall Room 182, 10900 University Blvd., Manassas, VA 20110, USA; (C.D.); (M.C.); (A.W.); (P.K.); (M.L.P.)
| | - Pooja Khatkar
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Discovery Hall Room 182, 10900 University Blvd., Manassas, VA 20110, USA; (C.D.); (M.C.); (A.W.); (P.K.); (M.L.P.)
| | - Fardokht A. Abulwerdi
- Basic Research Laboratory, National Cancer Institute, Frederick, MD 21702, USA; (F.A.A.); (S.F.J.L.G.)
| | - Lisa Henderson
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (L.H.); (J.D.); (D.R.L.); (A.N.)
| | - Julia Denniss
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (L.H.); (J.D.); (D.R.L.); (A.N.)
| | - Michelle L. Pleet
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Discovery Hall Room 182, 10900 University Blvd., Manassas, VA 20110, USA; (C.D.); (M.C.); (A.W.); (P.K.); (M.L.P.)
| | - Delores R. Luttrell
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (L.H.); (J.D.); (D.R.L.); (A.N.)
| | - Iosif Vaisman
- Laboratory for Structural Bioinformatics, School of Systems Biology, George Mason University, Manassas, VA 20110, USA;
| | - Lance A. Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110, USA;
| | - Joseph Steiner
- Translational Neuroscience Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Stuart F. J. Le Grice
- Basic Research Laboratory, National Cancer Institute, Frederick, MD 21702, USA; (F.A.A.); (S.F.J.L.G.)
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; (L.H.); (J.D.); (D.R.L.); (A.N.)
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Discovery Hall Room 182, 10900 University Blvd., Manassas, VA 20110, USA; (C.D.); (M.C.); (A.W.); (P.K.); (M.L.P.)
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Verkhratsky A, Butt A, Li B, Illes P, Zorec R, Semyanov A, Tang Y, Sofroniew MV. Astrocytes in human central nervous system diseases: a frontier for new therapies. Signal Transduct Target Ther 2023; 8:396. [PMID: 37828019 PMCID: PMC10570367 DOI: 10.1038/s41392-023-01628-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 08/15/2023] [Accepted: 08/22/2023] [Indexed: 10/14/2023] Open
Abstract
Astroglia are a broad class of neural parenchymal cells primarily dedicated to homoeostasis and defence of the central nervous system (CNS). Astroglia contribute to the pathophysiology of all neurological and neuropsychiatric disorders in ways that can be either beneficial or detrimental to disorder outcome. Pathophysiological changes in astroglia can be primary or secondary and can result in gain or loss of functions. Astroglia respond to external, non-cell autonomous signals associated with any form of CNS pathology by undergoing complex and variable changes in their structure, molecular expression, and function. In addition, internally driven, cell autonomous changes of astroglial innate properties can lead to CNS pathologies. Astroglial pathophysiology is complex, with different pathophysiological cell states and cell phenotypes that are context-specific and vary with disorder, disorder-stage, comorbidities, age, and sex. Here, we classify astroglial pathophysiology into (i) reactive astrogliosis, (ii) astroglial atrophy with loss of function, (iii) astroglial degeneration and death, and (iv) astrocytopathies characterised by aberrant forms that drive disease. We review astroglial pathophysiology across the spectrum of human CNS diseases and disorders, including neurotrauma, stroke, neuroinfection, autoimmune attack and epilepsy, as well as neurodevelopmental, neurodegenerative, metabolic and neuropsychiatric disorders. Characterising cellular and molecular mechanisms of astroglial pathophysiology represents a new frontier to identify novel therapeutic strategies.
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Affiliation(s)
- Alexei Verkhratsky
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China.
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania.
| | - Arthur Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, UK
| | - Baoman Li
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
| | - Peter Illes
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04109, Leipzig, Germany
| | - Robert Zorec
- Celica Biomedical, Lab Cell Engineering, Technology Park, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Faculty of Medicine, Ljubljana, Slovenia
| | - Alexey Semyanov
- Department of Physiology, Jiaxing University College of Medicine, 314033, Jiaxing, China
| | - Yong Tang
- International Joint Research Centre on Purinergic Signalling/School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
- Key Laboratory of Acupuncture for Senile Disease (Chengdu University of TCM), Ministry of Education/Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China.
| | - Michael V Sofroniew
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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Chen W, Zhu L, Shen LL, Si SY, Liu JL. T Lymphocyte Subsets Profile and Toll-Like Receptors Responses in Patients with Herpes Zoster. J Pain Res 2023; 16:1581-1594. [PMID: 37220634 PMCID: PMC10200109 DOI: 10.2147/jpr.s405157] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 05/05/2023] [Indexed: 05/25/2023] Open
Abstract
Purpose Herpes zoster (HZ) is caused by the varicella-zoster virus (VZV), and 20% of healthy humans and 50% of people with immune dysfunction have a high probability of suffering from HZ. This study aimed to screen dynamic immune signatures and explore the potential mechanism during HZ progression. Patients and Methods Peripheral blood samples from 31 HZ patients and 32 age-sex-matched healthy controls were collected and analyzed. The protein levels and gene levels of toll-like receptors (TLRs) were detected in peripheral blood mononuclear cells (PBMCs) by flow cytometry and quantitative real-time PCR. Further, the characteristics of T cell subsets and cytokines were detected via a cytometric bead array. Results Compared to healthy controls, the mRNA levels of TLR2, TLR4, TLR7, and TLR9 mRNA in PBMCs were significantly increased in HZ patients. The protein level of TLR4 and TLR7 was significantly increased in HZ patients, but the levels of TLR2 and TLR9 were dramatically decreased. The CD3+ T cells were constant in HZ and healthy controls. CD4+ T cells were decreased in HZ patients, while CD8+ T cells were increased, resulting in an improved CD4+/CD8+ T cells ratio. Further, it was found that Th2 and Th17 were not changed, but the decreased Th1 and upregulated Treg cells were found in HZ. The Th1/Th2 and Th17/Treg ratios were significantly decreased. Last, the levels of IL-6, IL-10, and IFN-γ were significantly increased, but IL-2, IL-4, and IL-17A had no significant changes. Conclusion The dysfunction of host's lymphocytes and activation of TLRs in PBMCs were the important mechanism in varicella-zoster virus induced herpes zoster. TLRs might be the core targets for the therapy drug development in treating HZ.
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Affiliation(s)
- Wei Chen
- Dermatology, Zhejiang Provincial Dermatology Hospital, Huzhou, Zhejiang, People’s Republic of China
| | - Lu Zhu
- Dermatology, Zhejiang Provincial Dermatology Hospital, Huzhou, Zhejiang, People’s Republic of China
| | - Li-Ling Shen
- Dermatology, Zhejiang Provincial Dermatology Hospital, Huzhou, Zhejiang, People’s Republic of China
| | - Shao-Yan Si
- Department of Comprehensive Basic Experiment, Strategic Support Force Medical Center, Bejing, People’s Republic of China
| | - Jun-Lian Liu
- Dermatology, Chui Yang Liu Hospital Affiliated Tsinghua University, Beijing, People’s Republic of China
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Brsikyan LA, Poluektova EA, Poluektov MG. The gut microbiome as a factor in the development of Parkinson's disease. NEUROLOGY, NEUROPSYCHIATRY, PSYCHOSOMATICS 2023. [DOI: 10.14412/2074-2711-2023-1-90-96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Affiliation(s)
- L. A. Brsikyan
- I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University)
| | - E. A. Poluektova
- I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University)
| | - M. G. Poluektov
- I.M. Sechenov First Moscow State Medical University of the Ministry of Health of Russia (Sechenov University)
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Pajarillo E, Nyarko-Danquah I, Digman A, Vied C, Son DS, Lee J, Aschner M, Lee E. Astrocytic Yin Yang 1 is critical for murine brain development and protection against apoptosis, oxidative stress, and inflammation. Glia 2023; 71:450-466. [PMID: 36300569 PMCID: PMC9772165 DOI: 10.1002/glia.24286] [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: 05/27/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 12/24/2022]
Abstract
The transcription factor Yin Yang 1 (YY1) is ubiquitously expressed in mammalian cells, regulating the expression of a variety of genes involved in proliferation, differentiation, and apoptosis in a context-dependent manner. While it is well-established that global YY1 knockout (KO) leads to embryonic death in mice and that YY1 deletion in neurons or oligodendrocytes induces impaired brain function, the role of astrocytic YY1 in the brain remains unknown. We investigated the role of astrocytic YY1 in the brain using a glial fibrillary acidic protein (GFAP)-specific YY1 conditional KO (YY1 cKO) mouse model to delete astrocytic YY1. Astrocytic YY1 cKO mice were tested for behavioral phenotypes, such as locomotor activity, coordination, and cognition, followed by an assessment of relevant biological pathways using RNA-sequencing analysis, immunoblotting, and immunohistochemistry in the cortex, midbrain, and cerebellum. YY1 cKO mice showed abnormal phenotypes, movement deficits, and cognitive dysfunction. At the molecular level, astrocytic YY1 deletion altered the expression of genes associated with proliferation and differentiation, p53/caspase apoptotic pathways, oxidative stress response, and inflammatory signaling including NF-κB, STAT, and IRF in all regions. Astrocytic YY1 deletion significantly increased the expression of GFAP as astrocytic activation and Iba1 as microglial activation, indicating astrocytic YY1 deletion activated microglia as well. Accordingly, multiple inflammatory cytokines and chemokines including TNF-α and CXCL10 were elevated. Combined, these novel findings suggest that astrocytic YY1 is a critical transcription factor for normal brain development and locomotor activity, motor coordination, and cognition. Astrocytic YY1 is also essential in preventing pathological oxidative stress, apoptosis, and inflammation.
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Affiliation(s)
- Edward Pajarillo
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, USA 32307
| | - Ivan Nyarko-Danquah
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, USA 32307
| | - Alexis Digman
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, USA 32307
| | - Cynthia Vied
- Translational Science Laboratory, Florida State University College of Medicine, Tallahassee, FL, USA 32306
| | - Deok-Soo Son
- Department of Biochemistry, Cancer Biology, Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee, USA 37208
| | - Jayden Lee
- Department of Speech, Language and Hearing Sciences, Boston University, Boston, MA, USA 02215
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, New York, USA, 10461
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, USA 32307
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Expression of Steroid Receptor RNA Activator 1 (SRA1) in the Adipose Tissue Is Associated with TLRs and IRFs in Diabesity. Cells 2022; 11:cells11244007. [PMID: 36552771 PMCID: PMC9776802 DOI: 10.3390/cells11244007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/04/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022] Open
Abstract
Steroid receptor RNA activator gene (SRA1) emerges as a player in pathophysiological responses of adipose tissue (AT) in metabolic disorders such as obesity and type 2 diabetes (T2D). We previously showed association of the AT SRA1 expression with inflammatory cytokines/chemokines involved in metabolic derangement. However, the relationship between altered adipose expression of SRA1 and the innate immune Toll-like receptors (TLRs) as players in nutrient sensing and metabolic inflammation as well as their downstream signaling partners, including interferon regulatory factors (IRFs), remains elusive. Herein, we investigated the association of AT SRA1 expression with TLRs, IRFs, and other TLR-downstream signaling mediators in a cohort of 108 individuals, classified based on their body mass index (BMI) as persons with normal-weight (N = 12), overweight (N = 32), and obesity (N = 64), including 55 with and 53 without T2D. The gene expression of SRA1, TLRs-2,3,4,7,8,9,10 and their downstream signaling mediators including IRFs-3,4,5, myeloid differentiation factor 88 (MyD88), interleukin-1 receptor-associated kinase 1 (IRAK1), and nuclear factor-κB (NF-κB) were determined using qRT-PCR and SRA1 protein expression was determined by immunohistochemistry. AT SRA1 transcripts' expression was significantly correlated with TLRs-3,4,7, MyD88, NF-κB, and IRF5 expression in individuals with T2D, while it associated with TLR9 and TRAF6 expression in all individuals, with/without T2D. SRA1 expression associated with TLR2, IRAK1, and IRF3 expression only in individuals with obesity, regardless of diabetes status. Furthermore, TLR3/TLR7/IRAK1 and TLR3/TLR9 were identified as independent predictors of AT SRA1 expression in individuals with obesity and T2D, respectively. Overall, our data demonstrate a direct association between the AT SRA1 expression and the TLRs together with their downstream signaling partners and IRFs in individuals with obesity and/or T2D.
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García-Martínez M, Cortez LM, Otero A, Betancor M, Serrano-Pérez B, Bolea R, Badiola JJ, Garza MC. Distinctive Toll-like Receptors Gene Expression and Glial Response in Different Brain Regions of Natural Scrapie. Int J Mol Sci 2022; 23:ijms23073579. [PMID: 35408945 PMCID: PMC8998348 DOI: 10.3390/ijms23073579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 11/16/2022] Open
Abstract
Prion diseases are chronic and fatal neurodegenerative diseases characterized by the accumulation of disease-specific prion protein (PrPSc), spongiform changes, neuronal loss, and gliosis. Growing evidence shows that the neuroinflammatory response is a key component of prion diseases and contributes to neurodegeneration. Toll-like receptors (TLRs) have been proposed as important mediators of innate immune responses triggered in the central nervous system in other human neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. However, little is known about the role of TLRs in prion diseases, and their involvement in the neuropathology of natural scrapie has not been studied. We assessed the gene expression of ovine TLRs in four anatomically distinct brain regions in natural scrapie-infected sheep and evaluated the possible correlations between gene expression and the pathological hallmarks of prion disease. We observed significant changes in TLR expression in scrapie-infected sheep that correlate with the degree of spongiosis, PrPSc deposition, and gliosis in each of the regions studied. Remarkably, TLR4 was the only gene upregulated in all regions, regardless of the severity of neuropathology. In the hippocampus, we observed milder neuropathology associated with a distinct TLR gene expression profile and the presence of a peculiar microglial morphology, called rod microglia, described here for the first time in the brain of scrapie-infected sheep. The concurrence of these features suggests partial neuroprotection of the hippocampus. Finally, a comparison of the findings in naturallyinfected sheep versus an ovinized mouse model (tg338 mice) revealed distinct patterns of TLRgene expression.
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Affiliation(s)
- Mirta García-Martínez
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes, IA2, IIS Aragón, Universidad de Zaragoza, 50013 Zaragoza, Spain; (M.G.-M.); (M.B.); (R.B.); (J.J.B.)
| | - Leonardo M. Cortez
- Department of Medicine and Centre for Prions and Protein Folding Diseases, University of Alberta, Edmonton, AB T6G 2G3, Canada
- Correspondence: (L.M.C.); (A.O.)
| | - Alicia Otero
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes, IA2, IIS Aragón, Universidad de Zaragoza, 50013 Zaragoza, Spain; (M.G.-M.); (M.B.); (R.B.); (J.J.B.)
- Correspondence: (L.M.C.); (A.O.)
| | - Marina Betancor
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes, IA2, IIS Aragón, Universidad de Zaragoza, 50013 Zaragoza, Spain; (M.G.-M.); (M.B.); (R.B.); (J.J.B.)
| | - Beatriz Serrano-Pérez
- Agrotecnio-CERCA Center, Department of Animal Science, University of Lleida, 25198 Lleida, Spain;
| | - Rosa Bolea
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes, IA2, IIS Aragón, Universidad de Zaragoza, 50013 Zaragoza, Spain; (M.G.-M.); (M.B.); (R.B.); (J.J.B.)
| | - Juan J. Badiola
- Centro de Encefalopatías y Enfermedades Transmisibles Emergentes, IA2, IIS Aragón, Universidad de Zaragoza, 50013 Zaragoza, Spain; (M.G.-M.); (M.B.); (R.B.); (J.J.B.)
| | - María Carmen Garza
- Departamento de Anatomía e Histología Humanas, IIS Aragón, Universidad de Zaragoza, 50009 Zaragoza, Spain;
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TLR Signaling in Brain Immunity. Handb Exp Pharmacol 2021; 276:213-237. [PMID: 34761292 DOI: 10.1007/164_2021_542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Toll-like receptors (TLRs) comprise a group of transmembrane proteins with crucial roles in pathogen recognition, immune responses, and signal transduction. This family represented the first line of immune homeostasis in an evolutionarily conserved manner. Extensive researches in the past two decades had emphasized their structural and functional characteristics under both healthy and pathological conditions. In this review, we summarized the current understanding of TLR signaling in the central nervous system (CNS), which had been viewed as a previously "immune-privileged" but now "immune-specialized" area, with major implications for further investigation of pathological nature as well as potential therapeutic manipulation of TLR signaling in various neurological disorders.
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Gern OL, Mulenge F, Pavlou A, Ghita L, Steffen I, Stangel M, Kalinke U. Toll-like Receptors in Viral Encephalitis. Viruses 2021; 13:v13102065. [PMID: 34696494 PMCID: PMC8540543 DOI: 10.3390/v13102065] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 12/23/2022] Open
Abstract
Viral encephalitis is a rare but serious syndrome. In addition to DNA-encoded herpes viruses, such as herpes simplex virus and varicella zoster virus, RNA-encoded viruses from the families of Flaviviridae, Rhabdoviridae and Paramyxoviridae are important neurotropic viruses. Whereas in the periphery, the role of Toll-like receptors (TLR) during immune stimulation is well understood, TLR functions within the CNS are less clear. On one hand, TLRs can affect the physiology of neurons during neuronal progenitor cell differentiation and neurite outgrowth, whereas under conditions of infection, the complex interplay between TLR stimulated neurons, astrocytes and microglia is just on the verge of being understood. In this review, we summarize the current knowledge about which TLRs are expressed by cell subsets of the CNS. Furthermore, we specifically highlight functional implications of TLR stimulation in neurons, astrocytes and microglia. After briefly illuminating some examples of viral evasion strategies from TLR signaling, we report on the current knowledge of primary immunodeficiencies in TLR signaling and their consequences for viral encephalitis. Finally, we provide an outlook with examples of TLR agonist mediated intervention strategies and potentiation of vaccine responses against neurotropic virus infections.
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Affiliation(s)
- Olivia Luise Gern
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, 30625 Hannover, Germany; (F.M.); (A.P.); (L.G.); (U.K.)
- Department of Pathology, University of Veterinary Medicine Hannover, Foundation, 30559 Hannover, Germany
- Correspondence:
| | - Felix Mulenge
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, 30625 Hannover, Germany; (F.M.); (A.P.); (L.G.); (U.K.)
| | - Andreas Pavlou
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, 30625 Hannover, Germany; (F.M.); (A.P.); (L.G.); (U.K.)
- Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, 30625 Hannover, Germany
- Center for Systems Neuroscience, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Luca Ghita
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, 30625 Hannover, Germany; (F.M.); (A.P.); (L.G.); (U.K.)
- Division of Infectious Diseases and Geographic Medicine, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Imke Steffen
- Department of Biochemistry and Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, 30559 Hannover, Germany;
| | - Martin Stangel
- Translational Medicine, Novartis Institute for Biomedical Research (NIBR), 4056 Basel, Switzerland;
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, 30625 Hannover, Germany; (F.M.); (A.P.); (L.G.); (U.K.)
- Cluster of Excellence—Resolving Infection Susceptibility (RESIST, EXC 2155), Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
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11
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Kwon J, Arsenis C, Suessmilch M, McColl A, Cavanagh J, Morris BJ. Differential Effects of Toll-Like Receptor Activation and Differential Mediation by MAP Kinases of Immune Responses in Microglial Cells. Cell Mol Neurobiol 2021; 42:2655-2671. [PMID: 34297254 PMCID: PMC9560989 DOI: 10.1007/s10571-021-01127-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/10/2021] [Indexed: 10/26/2022]
Abstract
Microglial activation is believed to play a role in many psychiatric and neurodegenerative diseases. Based largely on evidence from other cell types, it is widely thought that MAP kinase (ERK, JNK and p38) signalling pathways contribute strongly to microglial activation following immune stimuli acting on toll-like receptor (TLR) 3 or TLR4. We report here that exposure of SimA9 mouse microglial cell line to immune mimetics stimulating TLR4 (lipopolysaccharide-LPS) or TLR7/8 (resiquimod/R848), results in marked MAP kinase activation, followed by induction of nitric oxide synthase, and various cytokines/chemokines. However, in contrast to TLR4 or TLR7/8 stimulation, very few effects of TLR3 stimulation by poly-inosine/cytidine (polyI:C) were detected. Induction of chemokines/cytokines at the mRNA level by LPS and resiquimod were, in general, only marginally affected by MAP kinase inhibition, and expression of TNF, Ccl2 and Ccl5 mRNAs, along with nitrite production, were enhanced by p38 inhibition in a stimulus-specific manner. Selective JNK inhibition enhanced Ccl2 and Ccl5 release. Many distinct responses to stimulation of TLR4 and TLR7 were observed, with JNK mediating TNF protein induction by the latter but not the former, and suppressing Ccl5 release by the former but not the latter. These data reveal complex modulation by MAP kinases of microglial responses to immune challenge, including a dampening of some responses. They demonstrate that abnormal levels of JNK or p38 signalling in microglial cells will perturb their profile of cytokine and chemokine release, potentially contributing to abnormal inflammatory patterns in CNS disease states.
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Affiliation(s)
- Jaedeok Kwon
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK.,Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Christos Arsenis
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK
| | - Maria Suessmilch
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Alison McColl
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Jonathan Cavanagh
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Brian J Morris
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK.
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12
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Ghita L, Breitkopf V, Mulenge F, Pavlou A, Gern OL, Durán V, Prajeeth CK, Kohls M, Jung K, Stangel M, Steffen I, Kalinke U. Sequential MAVS and MyD88/TRIF signaling triggers anti-viral responses of tick-borne encephalitis virus-infected murine astrocytes. J Neurosci Res 2021; 99:2478-2492. [PMID: 34296786 DOI: 10.1002/jnr.24923] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/22/2021] [Accepted: 06/25/2021] [Indexed: 12/17/2022]
Abstract
Tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, is typically transmitted upon tick bite and can cause meningitis and encephalitis in humans. In TBEV-infected mice, mitochondrial antiviral-signaling protein (MAVS), the downstream adaptor of retinoic acid-inducible gene-I (RIG-I)-like receptor (RLR) signaling, is needed to induce early type I interferon (IFN) responses and to confer protection. To characterize the brain-resident cell subset that produces protective IFN-β in TBEV-infected mice, we isolated neurons, astrocytes, and microglia from mice and exposed these cell types to TBEV in vitro. Under such conditions, neurons showed the highest percentage of infected cells, whereas astrocytes and microglia were infected to a lesser extent. In the supernatant (SN) of infected neurons, IFN-β was not detectable, while infected astrocytes showed high and microglia low IFN-β expression. Transcriptome analyses of astrocytes implied that MAVS signaling was needed early after TBEV infection. Accordingly, MAVS-deficient astrocytes showed enhanced TBEV infection and significantly reduced early IFN-β responses. Nevertheless, at later time points, moderate amounts of IFN-β were detected in the SN of infected MAVS-deficient astrocytes. Transcriptome analyses indicated that MAVS deficiency negatively affected the induction of early anti-viral responses, which resulted in significantly increased TBEV replication. Treatment with MyD88 and TRIF inhibiting peptides reduced only late IFN-β responses of TBEV-infected WT astrocytes and blocked entirely IFN-β responses of infected MAVS-deficient astrocytes. Thus, upon TBEV exposure of brain-resident cells, astrocytes are important IFN-β producers showing biphasic IFN-β induction that initially depends on MAVS and later on MyD88/TRIF signaling.
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Affiliation(s)
- Luca Ghita
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Veronika Breitkopf
- Institute for Biochemistry and Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Felix Mulenge
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Andreas Pavlou
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.,Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Olivia Luise Gern
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.,Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Verónica Durán
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Chittappen Kandiyil Prajeeth
- Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Moritz Kohls
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Klaus Jung
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Martin Stangel
- Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Hannover, Germany.,Cluster of Excellence - Resolving Infection Susceptibility (RESIST, EXC 2155), Hannover Medical School, Hannover, Germany
| | - Imke Steffen
- Institute for Biochemistry and Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany.,Cluster of Excellence - Resolving Infection Susceptibility (RESIST, EXC 2155), Hannover Medical School, Hannover, Germany
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13
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Martinez NW, Gómez FE, Matus S. The Potential Role of Protein Kinase R as a Regulator of Age-Related Neurodegeneration. Front Aging Neurosci 2021; 13:638208. [PMID: 33994991 PMCID: PMC8113420 DOI: 10.3389/fnagi.2021.638208] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/10/2021] [Indexed: 01/25/2023] Open
Abstract
There is a growing evidence describing a decline in adaptive homeostasis in aging-related diseases affecting the central nervous system (CNS), many of which are characterized by the appearance of non-native protein aggregates. One signaling pathway that allows cell adaptation is the integrated stress response (ISR), which senses stress stimuli through four kinases. ISR activation promotes translational arrest through the phosphorylation of the eukaryotic translation initiation factor 2 alpha (eIF2α) and the induction of a gene expression program to restore cellular homeostasis. However, depending on the stimulus, ISR can also induce cell death. One of the ISR sensors is the double-stranded RNA-dependent protein kinase [protein kinase R (PKR)], initially described as a viral infection sensor, and now a growing evidence supports a role for PKR on CNS physiology. PKR has been largely involved in the Alzheimer’s disease (AD) pathological process. Here, we reviewed the antecedents supporting the role of PKR on the efficiency of synaptic transmission and cognition. Then, we review PKR’s contribution to AD and discuss the possible participation of PKR as a player in the neurodegenerative process involved in aging-related pathologies affecting the CNS.
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Affiliation(s)
- Nicolás W Martinez
- Fundación Ciencia & Vida, Santiago, Chile.,Departamento de Ciencias Básicas, Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
| | | | - Soledad Matus
- Fundación Ciencia & Vida, Santiago, Chile.,Departamento de Ciencias Básicas, Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
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14
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Abstract
The adipose tissue has been recognized as an active organ involved in numerous metabolic, hormonal and immunological processes. Obesity and associated chronic inflammation leads to many metabolic and autoimmune disorders. The number of cells, their phenotype and distribution in adipose tissue depends on the degree of obesity. Polarization of macrophages towards M1, neutrophils influx to adipose tissue, activation of Th1 and Th17 cells and increased level of proinflammatory cytokines are characteristic for obesity-induced inflammation. Several mechanisms, such as adipocytes’ hypoxia, oxidative stress, endoplasmic reticulum stress, impairment of PPAR receptors, inflammasomes’ activation and activation of TLR are involved into development of chronic obesity-induced inflammation. A better understanding of this processes can provide new treatments for obesity and related disorders.
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15
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Sangaran PG, Ibrahim ZA, Chik Z, Mohamed Z, Ahmadiani A. LPS Preconditioning Attenuates Apoptosis Mechanism by Inhibiting NF-κB and Caspase-3 Activity: TLR4 Pre-activation in the Signaling Pathway of LPS-Induced Neuroprotection. Mol Neurobiol 2021; 58:2407-2422. [PMID: 33421016 DOI: 10.1007/s12035-020-02227-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 11/24/2020] [Indexed: 12/11/2022]
Abstract
Neuroinflammation, an inflammatory response within the nervous system, has been shown to be implicated in the progression of various neurodegenerative diseases. Recent in vivo studies showed that lipopolysaccharide (LPS) preconditioning provides neuroprotection by activating Toll-like receptor 4 (TLR4), one of the members for pattern recognition receptor (PRR) family that play critical role in host response to tissue injury, infection, and inflammation. Pre-exposure to low dose of LPS could confer a protective state against cellular apoptosis following subsequent stimulation with LPS at higher concentration, suggesting a role for TLR4 pre-activation in the signaling pathway of LPS-induced neuroprotection. However, the precise molecular mechanism associated with this protective effect is not well understood. In this article, we provide an overall review of the current state of our knowledge about LPS preconditioning in attenuating apoptosis mechanism and conferring neuroprotection via TLR4 signaling pathway.
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Affiliation(s)
- Pushpa Gandi Sangaran
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Zaridatul Aini Ibrahim
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Zamri Chik
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Zahurin Mohamed
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Abolhassan Ahmadiani
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, Evin, PO Box 19839-63113, Tehran, Iran.
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16
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Cawthon CR, Kirkland RA, Pandya S, Brinson NA, de La Serre CB. Non-neuronal crosstalk promotes an inflammatory response in nodose ganglia cultures after exposure to byproducts from gram positive, high-fat-diet-associated gut bacteria. Physiol Behav 2020; 226:113124. [PMID: 32763334 PMCID: PMC7530053 DOI: 10.1016/j.physbeh.2020.113124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 07/31/2020] [Accepted: 08/03/2020] [Indexed: 02/06/2023]
Abstract
Vagal afferent neurons (VAN) projecting to the lamina propria of the digestive tract are the primary source of gut-originating signals to the central nervous system (CNS). VAN cell bodies are found in the nodose ganglia (NG). Responsiveness of VAN to gut-originating signals is altered by feeding status with sensitivity to satiety signals such as cholecystokinin (CCK) increasing in the fed state. Chronic high-fat (HF) feeding results in inflammation at the level of the NG associated with a loss of VAN ability to switch phenotype from the fasted to the fed state. HF feeding also leads to compositional changes in the gut microbiota. HF diet consumption notably drives increased Firmicutes to Bacteroidetes phyla ratio and increased members of the Actinobacteria phylum. Firmicutes and Actinobacteria are largely gram positive (GP). In this study, we aimed to determine if byproducts from GP bacteria can induce an inflammatory response in cultured NG and to characterize the mechanism and cell types involved in the response. NG were collected from male Wistar rats and cultured for a total of 72 hours. At 48-68 hours after plating, cultures were treated with neuronal culture media in which Serinicoccus chungangensis had been grown and removed (SUP), lipoteichoic acid (LTA), or meso-diaminopimelic acid (meso-DAP). Some treatments included the glial inhibitors minocycline (MINO) and/or fluorocitrate (FC). The responses were evaluated using immunocytochemistry, qPCR, and electrochemiluminescence. We found that SUP induced an inflammatory response characterized by increased interleukin (IL)-6 staining and increased expression of genes for IL-6, interferon (IFN)γ, and tumor necrosis factor (TNF)α along with genes associated with cell-to-cell communication such as C-C motif chemokine ligand-2 (CCL2). Inclusion of inhibitors attenuated some responses but failed to completely normalize all indications of response, highlighting the role of immunocompetent cellular crosstalk in regulating the inflammatory response. LTA and meso-DAP produced responses that shared characteristics with SUP but were not identical. Our results support a role for HF associated GP bacterial byproducts' ability to contribute to vagal inflammation and to engage signaling from nonneuronal cells.
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Affiliation(s)
- Carolina R Cawthon
- Department of Foods and Nutrition, The University of Georgia, Athens, Georgia30602, United States
| | - Rebecca A Kirkland
- Department of Foods and Nutrition, The University of Georgia, Athens, Georgia30602, United States
| | - Shreya Pandya
- Department of Foods and Nutrition, The University of Georgia, Athens, Georgia30602, United States
| | - Nigel A Brinson
- Department of Foods and Nutrition, The University of Georgia, Athens, Georgia30602, United States
| | - Claire B de La Serre
- Department of Foods and Nutrition, The University of Georgia, Athens, Georgia30602, United States.
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17
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Toll-Like Receptor 2 Attenuates Traumatic Brain Injury-Induced Neural Stem Cell Proliferation in Dentate Gyrus of Rats. Neural Plast 2020; 2020:9814978. [PMID: 32879625 PMCID: PMC7448220 DOI: 10.1155/2020/9814978] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/10/2020] [Accepted: 07/24/2020] [Indexed: 01/06/2023] Open
Abstract
It was not clear how and whether neural stem cells (NSCs) responded to toll-like receptor 2 (TLR2) in the inflammatory environment after traumatic brain injury (TBI). The current study investigated the correlation of TLR2 and NSC proliferation in the dentate gyrus (DG) using the TBI model of rats. Immunofluorescence (IF) was used to observe the expression of BrdU, nestin, and TLR2 in the DG in morphology. Proliferating cells in the DG were labelled by thymidine analog 5-bromo-2-deoxyuridine (BrdU). Three-labelled BrdU, nestin, and DAPI was used for the identification of newly generated NSCs. Western blotting and real-time polymerase chain reaction (PCR) were used to observe the expression of TLR2 from the level of protein and mRNA. We observed that BrdU+/nestin+/DAPI+ cells accounted for 84.30% ± 6.54% among BrdU+ cells; BrdU+ and nestin+ cells in the DG were also TLR2+ cells. BrdU+ cells and the expression of TLR2 (both protein and mRNA levels) both elevated immediately at 6 hours (h), 24 h, 3 days (d), and 7 d posttrauma and peaked in 3 d. Results indicated that TLR2 was expressed on proliferating cells in the DG (NSCs possibly) and there was a potential correlation between increased TLR2 and proliferated NSCs after TBI. Taken together, these findings suggested that TLR2 was involved in endogenous neurogenesis in the DG after TBI.
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18
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Oo TT, Pratchayasakul W, Chattipakorn N, Chattipakorn SC. Potential Roles of Myeloid Differentiation Factor 2 on Neuroinflammation and Its Possible Interventions. Mol Neurobiol 2020; 57:4825-4844. [PMID: 32803490 DOI: 10.1007/s12035-020-02066-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/07/2020] [Indexed: 02/06/2023]
Abstract
Neuroinflammation is the primary response by immune cells in the nervous system to protect against infection. Chronic and uncontrolled neuroinflammation triggers neuronal injury and neuronal death resulting in a variety of neurodegenerative disorders. Therefore, fine tuning of the immune response in the nervous system is now extensively considered as a potential therapeutic intervention for those diseases. The immune cells of the nervous system express Toll-like receptor 4 (TLR4) together with myeloid differentiation factor 2 (MD-2) to protect against the pathogens. Over the last 10 years, antagonists targeting the functional domains of MD-2 have become attractive pharmacological intervention strategies in pre-clinical studies into neuroinflammation and its associated brain pathologies. This review aims to summarize and discuss the roles of TLR4-MD-2 signaling pathway activation in various models of neuroinflammation. This review article also highlights the studies reporting the effect of MD-2 antagonists on neuroinflammation in in vitro and in vivo studies.
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Affiliation(s)
- Thura Tun Oo
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand
| | - Wasana Pratchayasakul
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand
| | - Siriporn C Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand. .,Center of Excellence in Cardiac Electrophysiology, Chiang Mai University, Chiang Mai, Thailand. .,Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
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Polymannuronic acid prevents dopaminergic neuronal loss via brain-gut-microbiota axis in Parkinson's disease model. Int J Biol Macromol 2020; 164:994-1005. [PMID: 32710966 DOI: 10.1016/j.ijbiomac.2020.07.180] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 02/06/2023]
Abstract
The study aims to investigate the potentially neuroprotective effects and underlying mechanisms for brown seaweed polysaccharide of polymannuronic acid (PM) against Parkinson's disease (PD) pathogenesis. PD model mice were pretreated with PM via oral gavage once per day for 4 weeks and the preventative effects of PM against neuronal loss together with its modulation on brain-gut-microbiota axis were systematically explored. The results showed PM administration improved motor functions by preventing dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc) and enhanced contents of striatal homovanillic acid (HVA), serotonin (5-HT), 5-hydroxyindole acetic acid (5-HIAA) and γ-aminobutyric acid (GABA) in PD mice. PM significantly alleviated inflammation in gut, brain and systemic circulation as shown by reduced levels or expressions of pro-inflammatory cytokines concurrently and inhibited mitogen-activated protein kinases (MAPK) signaling pathway in mice colon. Meanwhile, PM greatly improved integrity of intestinal barrier and blood brain barrier (BBB) as indicated by increased expressions of tight junction associated proteins in both mice colon and SNpc. Further studies indicated PM treatment resulted in changes of gut microbial compositions, together with great alterations of digestion and metabolism of dietary proteins and fats, which led to surge increase of fecal short chain fatty acids (SCFAs) in the colon of PD mice. In conclusion, pre-administration of PM could provide neuroprotective effects against PD pathogenesis by suppressing inflammation in gut, brain and systemic circulation, and by improving integrity of intestinal barrier and BBB. PM might modulate brain-gut-microbiota axis, at least in part, via gut microbiota derived SCFAs as mediators.
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20
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The impact of vitamin D supplementation on VDR gene expression and body composition in monozygotic twins: randomized controlled trial. Sci Rep 2020; 10:11943. [PMID: 32686744 PMCID: PMC7371728 DOI: 10.1038/s41598-020-69128-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 07/07/2020] [Indexed: 02/07/2023] Open
Abstract
Vitamin D supplementation is widely used. However, there is no consensus on the use and dosage of this supplement and the existing recommendations arise from studies based on the benefits that this nutrient can facilitate in bones. In addition, individual genetics can influence the response to supplementation, therefore, research involving monozygotic twins aims to reduce these differences in phenotypic responses. The objective of this randomised controlled study is to examine the effect of vitamin D supplementation on body composition and the expression of the vitamin D receptor (VDR) mRNA. An intervention was performed through supplementation with cholecalciferol at the concentration of 2000 IU in 90 healthy adult monozygotic twins (male or female pairs) for 2 months. The findings showed that serum vitamin D concentration increased by 65% and VDR gene expression sixty times (p = 0.001). Changes in body composition parameters were observed regarding body fat and lean mass. Our results indicate that an increase in serum vitamin D concentration may have potential therapeutic implications.
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21
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Tibolone Ameliorates the Lipotoxic Effect of Palmitic Acid in Normal Human Astrocytes. Neurotox Res 2020; 38:585-595. [DOI: 10.1007/s12640-020-00247-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/13/2020] [Accepted: 06/17/2020] [Indexed: 02/06/2023]
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22
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Graykowski D, Kasparian K, Caniglia J, Gritsaeva Y, Cudaback E. Neuroinflammation drives APOE genotype-dependent differential expression of neprilysin. J Neuroimmunol 2020; 346:577315. [PMID: 32682137 DOI: 10.1016/j.jneuroim.2020.577315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/28/2020] [Accepted: 06/29/2020] [Indexed: 02/04/2023]
Abstract
Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by the deposition of amyloid-beta (Aβ) plaques and widespread neuroinflammation. While the cause of AD remains unknown, multiple factors likely contribute to the disease, including heart disease, diabetes, previous head injury, as well as a number of genetic determinants. Inheritance of the apolipoprotein (APOE) ε4 allele represents the strongest genetic risk factor for development of AD, driving pathogenesis and increasing overall disease severity. APOE has long been recognized as a key regulator of cholesterol homeostasis, although a greater appreciation now exists for its role in various innate immune system processes. Indeed, APOE modulates inflammatory environments in brain in large part by altering gene expression profiles in glia, important mediators of immunity in the CNS. While the association between APOE and AD was first observed nearly three decades ago, the mechanism by which APOE ε4 influences the etiology and pathophysiology of AD is not well characterized. Overwhelming data supports the hypothesis that APOE ε4 dysregulates central amyloid metabolism by an undetermined molecular mechanism, thus laying the foundation for disease. A host of amyloid-degrading enzymes (ADEs) regulate Aβ accumulation in brain, and therefore represent valuable therapeutic targets. Neprilysin (NEP), a metalloendopeptidase expressed by activated microglia and astrocytes, is a broad-spectrum ADE able to degrade a variety of Aβ species. Here we describe in vivo and in vitro experiments designed to investigate the potential for APOE genotype to differentially regulate glial NEP in brain under neuroinflammatory conditions. Our results provide a novel mechanism by which APOE genotype-dependent differential expression of NEP by glia during neuroinflammation may contribute to AD pathogenesis.
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Affiliation(s)
- David Graykowski
- Department of Health Sciences, DePaul University, Chicago, IL 60614, USA
| | - Kyle Kasparian
- Department of Health Sciences, DePaul University, Chicago, IL 60614, USA
| | - John Caniglia
- Department of Health Sciences, DePaul University, Chicago, IL 60614, USA
| | - Yelena Gritsaeva
- Department of Health Sciences, DePaul University, Chicago, IL 60614, USA
| | - Eiron Cudaback
- Department of Health Sciences, DePaul University, Chicago, IL 60614, USA.
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Telegin GB, Chernov AS, Konovalov NA, Belogurov AA, Balmasova IP, Gabibov AG. Cytokine Profile As a Marker of Cell Damage and Immune Dysfunction after Spinal Cord Injury. Acta Naturae 2020; 12:92-101. [PMID: 33173599 PMCID: PMC7604889 DOI: 10.32607/actanaturae.11096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/08/2020] [Indexed: 12/30/2022] Open
Abstract
This study reviews the findings of recent experiments designed to investigate the cytokine profile after a spinal cord injury. The role played by key cytokines in eliciting the cellular response to trauma was assessed. The results of the specific immunopathogenetic interaction between the nervous and immune systems in the immediate and chronic post-traumatic periods are summarized. It was demonstrated that it is reasonable to use the step-by-step approach to the assessment of the cytokine profile after a spinal cord injury and take into account the combination of the pathogenetic and protective components in implementing the regulatory effects of individual cytokines and their integration into the regenerative processes in the injured spinal cord. This allows one to rationally organize treatment and develop novel drugs.
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Affiliation(s)
- G. B. Telegin
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Pushchino, 142290 Russia
| | - A. S. Chernov
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Pushchino, 142290 Russia
| | - N. A. Konovalov
- N.N. Burdenko National Scientific and Practical Center for Neurosurgery, RF Health Ministry, Moscow, 125047 Russia
| | - A. A. Belogurov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, 117997 Russia
| | - I. P. Balmasova
- Evdokimov Moscow State University of Medicine and Dentistry of Russia’s Ministry of Health, Moscow, 127473 Russia
| | - A. G. Gabibov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, 117997 Russia
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Christoforidou E, Joilin G, Hafezparast M. Potential of activated microglia as a source of dysregulated extracellular microRNAs contributing to neurodegeneration in amyotrophic lateral sclerosis. J Neuroinflammation 2020; 17:135. [PMID: 32345319 PMCID: PMC7187511 DOI: 10.1186/s12974-020-01822-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 04/21/2020] [Indexed: 02/07/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron degeneration in adults, and several mechanisms underlying the disease pathology have been proposed. It has been shown that glia communicate with other cells by releasing extracellular vesicles containing proteins and nucleic acids, including microRNAs (miRNAs), which play a role in the post-transcriptional regulation of gene expression. Dysregulation of miRNAs is commonly observed in ALS patients, together with inflammation and an altered microglial phenotype. However, the role of miRNA-containing vesicles in microglia-to-neuron communication in the context of ALS has not been explored in depth. This review summarises the evidence for the presence of inflammation, pro-inflammatory microglia and dysregulated miRNAs in ALS, then explores how microglia may potentially be responsible for this miRNA dysregulation. The possibility of pro-inflammatory ALS microglia releasing miRNAs which may then enter neuronal cells to contribute to degeneration is also explored. Based on the literature reviewed here, microglia are a likely source of dysregulated miRNAs and potential mediators of neurodegenerative processes. Therefore, dysregulated miRNAs may be promising candidates for the development of therapeutic strategies.
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Affiliation(s)
| | - Greig Joilin
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | - Majid Hafezparast
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK.
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25
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Fraunberger E, Esser MJ. Neuro-Inflammation in Pediatric Traumatic Brain Injury-from Mechanisms to Inflammatory Networks. Brain Sci 2019; 9:E319. [PMID: 31717597 PMCID: PMC6895990 DOI: 10.3390/brainsci9110319] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 12/12/2022] Open
Abstract
Compared to traumatic brain injury (TBI) in the adult population, pediatric TBI has received less research attention, despite its potential long-term impact on the lives of many children around the world. After numerous clinical trials and preclinical research studies examining various secondary mechanisms of injury, no definitive treatment has been found for pediatric TBIs of any severity. With the advent of high-throughput and high-resolution molecular biology and imaging techniques, inflammation has become an appealing target, due to its mixed effects on outcome, depending on the time point examined. In this review, we outline key mechanisms of inflammation, the contribution and interactions of the peripheral and CNS-based immune cells, and highlight knowledge gaps pertaining to inflammation in pediatric TBI. We also introduce the application of network analysis to leverage growing multivariate and non-linear inflammation data sets with the goal to gain a more comprehensive view of inflammation and develop prognostic and treatment tools in pediatric TBI.
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Affiliation(s)
- Erik Fraunberger
- Alberta Children’s Hospital Research Institute, Calgary, AB T3B 6A8, Canada;
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Michael J. Esser
- Alberta Children’s Hospital Research Institute, Calgary, AB T3B 6A8, Canada;
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
- Department of Pediatrics, Cumming School Of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
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26
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Toll-like receptors and their therapeutic potential in Parkinson's disease and α-synucleinopathies. Brain Behav Immun 2019; 81:41-51. [PMID: 31271873 DOI: 10.1016/j.bbi.2019.06.042] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 06/13/2019] [Accepted: 06/29/2019] [Indexed: 01/05/2023] Open
Abstract
Toll-like receptors (TLRs) are pattern recognition receptors which mediate an inflammatory response upon the detection of specific molecular patterns found on foreign organisms and on endogenous damage-related molecules. These receptors play a major role in the activation of microglia, the innate immune cells of the CNS, and are also expressed in peripheral tissues, including blood mononuclear cells and the gut. It is well established that immune activation, in both the brain and periphery, is a feature of Parkinson's disease as well as other α-synucleinopathies. Aggregated forms of α-synuclein can act as ligands for TLRs (particularly TLR2 and TLR4), and hence these receptors may play a critical role in mediating a detrimental immune response to this protein, as well as other inflammatory signals in Parkinson's and related α-synucleinopathies. In this review, the potential role of TLRs in contributing to the progression of these disorders is discussed. Existing evidence comes predominantly from studies in in vitro and in vivo models, as well as analyses of postmortem human brain tissue and pre-clinical studies of TLR inhibitors. This evidence is evaluated in detail, and the potential for therapeutic intervention in α-synucleinopathies through TLR inhibition is discussed.
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Zhong S, Zhou Z, Liang Y, Cheng X, Li Y, Teng W, Zhao M, Liu C, Guan M, Zhao C. Targeting strategies for chemotherapy-induced peripheral neuropathy: does gut microbiota play a role? Crit Rev Microbiol 2019; 45:369-393. [PMID: 31106639 DOI: 10.1080/1040841x.2019.1608905] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a progressive, often irreversible condition that produces severe neurological deficits. Emerging data suggest that chemotherapy also exerts detrimental effects on gut microbiota composition and intestinal permeability, contributing to dysbiosis and inflammation. Compared with other complications associated with chemotherapy, such as diarrhoea and mucositis, CIPN is of particular concern because it is the most common reason for terminating or suspending treatment. However, specific and effective curative treatment strategies are lacking. In this review, we provide an update on current preclinical and clinical understandings about the role of gut microbiota in CIPN. The gut microbiota serves as an intersection between the microbiome-gut-brain and the neuroimmune-endocrine axis, forming a complex network that can directly or indirectly affect key components involved in the manifestations of CIPN. Herein, we discuss several potential mechanisms within the context of the networks and summarize alterations in gut microbiome induced by chemotherapeutic drugs, providing great potential for researchers to target pathways associated with the gut microbiome and overcome CIPN.
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Affiliation(s)
- Shanshan Zhong
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
| | - Zhike Zhou
- Department of Geriatrics, The First Hospital of China Medical University , Shenyang , PR China
| | - Yifan Liang
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
| | - Xi Cheng
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
| | - Yong Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University , Shenyang , PR China
| | - Weiyu Teng
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
| | - Mei Zhao
- Department of Cardiology, Shengjing Hospital of China Medical University , Shenyang , PR China
| | - Chang Liu
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
| | - Meiting Guan
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
| | - Chuansheng Zhao
- Department of Neurology and Stroke Center, The First Hospital of China Medical University , Shenyang , PR China
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Azam S, Jakaria M, Kim IS, Kim J, Haque ME, Choi DK. Regulation of Toll-Like Receptor (TLR) Signaling Pathway by Polyphenols in the Treatment of Age-Linked Neurodegenerative Diseases: Focus on TLR4 Signaling. Front Immunol 2019; 10:1000. [PMID: 31134076 PMCID: PMC6522942 DOI: 10.3389/fimmu.2019.01000] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/18/2019] [Indexed: 12/13/2022] Open
Abstract
Neuronal dysfunction initiates several intracellular signaling cascades to release different proinflammatory cytokines and chemokines, as well as various reactive oxygen species. In addition to neurons, microglia, and astrocytes are also affected by this signaling cascade. This release can either be helpful, neutral or detrimental for cell survival. Toll-like receptors (TLRs) activate and signal their downstream pathway to activate NF-κB and pro-IL-1β, both of which are responsible for neuroinflammation and linked to the pathogenesis of different age-related neurological conditions. However, herein, recent aspects of polyphenols in the treatment of neurodegenerative diseases are assessed, with a focus on TLR regulation by polyphenols. Different polyphenol classes, including flavonoids, phenolic acids, phenolic alcohols, stilbenes, and lignans can potentially target TLR signaling in a distinct pathway. Further, some polyphenols can suppress overexpression of inflammatory mediators through TLR4/NF-κB/STAT signaling intervention, while others can reduce neuronal apoptosis via modulating the TLR4/MyD88/NF-κB-pathway in microglia/macrophages. Indeed, neurodegeneration etiology is complex and yet to be completely understood, it may be that targeting TLRs could reveal a number of molecular and pharmacological aspects related to neurodegenerative diseases. Thus, activating TLR signaling modulation via natural resources could provide new therapeutic potentiality in the treatment of neurodegeneration.
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Affiliation(s)
- Shofiul Azam
- Department of Applied Life Science & Integrated Bioscience, Graduate School, Konkuk University, Chungju-si, South Korea
| | - Md Jakaria
- Department of Applied Life Science & Integrated Bioscience, Graduate School, Konkuk University, Chungju-si, South Korea
| | - In-Su Kim
- Department of Integrated Bioscience & Biotechnology, Research Institute of Inflammatory Disease (RID), College of Biomedical and Health Science, Konkuk University, Chungju-si, South Korea
| | - Joonsoo Kim
- Department of Applied Life Science & Integrated Bioscience, Graduate School, Konkuk University, Chungju-si, South Korea
| | - Md Ezazul Haque
- Department of Applied Life Science & Integrated Bioscience, Graduate School, Konkuk University, Chungju-si, South Korea
| | - Dong-Kug Choi
- Department of Applied Life Science & Integrated Bioscience, Graduate School, Konkuk University, Chungju-si, South Korea.,Department of Integrated Bioscience & Biotechnology, Research Institute of Inflammatory Disease (RID), College of Biomedical and Health Science, Konkuk University, Chungju-si, South Korea
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29
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Herrera-Rivero M, Santarelli F, Brosseron F, Kummer MP, Heneka MT. Dysregulation of TLR5 and TAM Ligands in the Alzheimer’s Brain as Contributors to Disease Progression. Mol Neurobiol 2019; 56:6539-6550. [DOI: 10.1007/s12035-019-1540-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 02/25/2019] [Indexed: 01/09/2023]
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Noailles A, Kutsyr O, Maneu V, Ortuño-Lizarán I, Campello L, de Juan E, Gómez-Vicente V, Cuenca N, Lax P. The Absence of Toll-Like Receptor 4 Mildly Affects the Structure and Function in the Adult Mouse Retina. Front Cell Neurosci 2019; 13:59. [PMID: 30873007 PMCID: PMC6401850 DOI: 10.3389/fncel.2019.00059] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 02/05/2019] [Indexed: 12/26/2022] Open
Abstract
The innate immune Toll-like receptor (TLR) family plays essential roles in cell proliferation, survival and function of the central nervous system. However, the way in which TLRs contribute to the development and maintenance of proper retinal structure and function remains uncertain. In this work, we assess the effect of genetic TLR4 deletion on the morphology and function of the retina in mice. Visual acuity and retinal responsiveness were evaluated in TLR4 knockout and wild type C57BL/6J control mice by means of an optomotor test and electroretinography, respectively, from P20 to P360. Retinal structure was also analyzed in both strains using confocal and electron microscopy. ERG data showed impaired retinal responsiveness in TLR4 KO mice, in comparison to wild type animals. The amplitudes of the scotopic a-waves were less pronounced in TLR4-deficient mice than in wild-type animals from P30 to P360, and TLR4 KO mice presented scotopic b-wave amplitudes smaller than those of age-matched control mice at all ages studied (P20 to P360). Visual acuity was also relatively poorer in TLR4 KO as compared to C57BL/6J mice from P20 to P360, with significant differences at P30 and P60. Immunohistochemical analysis of retinal vertical sections showed no differences between TLR4 KO and C57BL/6J mice, in terms of either photoreceptor number or photoreceptor structure. Horizontal cells also demonstrated no morphological differences between TLR4 KO and wild-type mice. However, TLR4 KO mice exhibited a lower density of bipolar cells (15% less at P30) and thus fewer bipolar cell dendrites than the wild type control mouse, even though both confocal and electron microscopy images showed no morphologic abnormalities in the synaptic contacts between the photoreceptors and second order neurons. Microglial cell density was significantly lower (26% less at P30) in TLR4 KO mice as compared to wild-type control mice. These results suggest that TLR4 deletion causes functional alterations in terms of visual response and acuity, probably through the loss of bipolar cells and microglia, but this receptor is not essential for the processing of visual information in the retina.
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Affiliation(s)
- Agustina Noailles
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Oksana Kutsyr
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Isabel Ortuño-Lizarán
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Laura Campello
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Emilio de Juan
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Violeta Gómez-Vicente
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain.,Institute Ramón Margalef, University of Alicante, Alicante, Spain
| | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
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Sarni AR, Baroni L. Milk and Parkinson disease: Could galactose be the missing link. MEDITERRANEAN JOURNAL OF NUTRITION AND METABOLISM 2019. [DOI: 10.3233/mnm-180234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | - Luciana Baroni
- Primary Care Unit, Northern District, Local Health Unit 2 Marca Trevigiana, Treviso, Italy
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Butnaru D, Chapman J. The impact of self-replicating proteins on inflammation, autoimmunity and neurodegeneration-An untraveled path. Autoimmun Rev 2019; 18:231-240. [PMID: 30639644 DOI: 10.1016/j.autrev.2018.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 09/12/2018] [Indexed: 02/08/2023]
Abstract
The central nervous system (CNS) in neurodegenerative diseases is a battlefield in which microglia fight a highly atypical battle. During the inflammatory process microglia themselves become dysfunctional and even with all the available immune arsenal including cytokine or/and antibody production, the battle is eventually lost. A closer look into the picture will reveal the fact that this is mainly due to the atypical characteristics of the infectious agent. The supramolecular assemblies of misfolded proteins carry unique features not encountered in any of the common pathogens. Through misfolding, proteins undergo conformational changes which make them become immunogenic, neurotoxic and highly infective. The immunogenicity appears to be triggered by the exposure of previously hidden hydrophobic portions in proteins which act as damage-associated molecular patters (DAMPs) for the immune system. The neurotoxicity and infectivity are promoted by the small oligomeric forms of misfolded proteins/peptides. Oligomers adopt conformations such as tubular-like, beta-barrel-like, etc., that penetrate cell membranes through their hydrophobic surfaces, thus destabilizing ionic homeostasis. At the same time, oligomers act as a seed for protein misfolding through a prion/prion-like mechanism. Here, we propose the hypothesis that oligomers have catalytic surfaces and exercise their capacity to infect native proteins through specific characteristics such as hydrophobic, electrostatic and π-π stacking interactions as well as the specific surface area (SSA), surface curvature and surface chemistry of their nanoscale supramolecular assemblies. All these are the key elements for prion/prion-like mechanism of self-replication and disease spreading within the CNS. Thus, understanding the mechanism of prion's templating activity may help us in the prevention and development of novel therapeutic strategies for neurodegenerative diseases.
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Affiliation(s)
- Dana Butnaru
- The Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, Tel Hashomer, Israel.
| | - Joab Chapman
- Sheba Medical Center, Israel; Robert and Martha Harden Chair in Mental and Neurological Diseases, Sackler Faculty of Medicine, Tel Aviv University, Israel
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Hypothalamic Inflammation at a Crossroad of Somatic Diseases. Cell Mol Neurobiol 2018; 39:11-29. [DOI: 10.1007/s10571-018-0631-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/24/2018] [Indexed: 02/08/2023]
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Toll-like receptors in immunity and inflammatory diseases: Past, present, and future. Int Immunopharmacol 2018; 59:391-412. [PMID: 29730580 PMCID: PMC7106078 DOI: 10.1016/j.intimp.2018.03.002] [Citation(s) in RCA: 387] [Impact Index Per Article: 64.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 02/28/2018] [Accepted: 03/01/2018] [Indexed: 02/07/2023]
Abstract
The immune system is a very diverse system of the host that evolved during evolution to cope with various pathogens present in the vicinity of environmental surroundings inhabited by multicellular organisms ranging from achordates to chordates (including humans). For example, cells of immune system express various pattern recognition receptors (PRRs) that detect danger via recognizing specific pathogen-associated molecular patterns (PAMPs) and mount a specific immune response. Toll-like receptors (TLRs) are one of these PRRs expressed by various immune cells. However, they were first discovered in the Drosophila melanogaster (common fruit fly) as genes/proteins important in embryonic development and dorso-ventral body patterning/polarity. Till date, 13 different types of TLRs (TLR1-TLR13) have been discovered and described in mammals since the first discovery of TLR4 in humans in late 1997. This discovery of TLR4 in humans revolutionized the field of innate immunity and thus the immunology and host-pathogen interaction. Since then TLRs are found to be expressed on various immune cells and have been targeted for therapeutic drug development for various infectious and inflammatory diseases including cancer. Even, Single nucleotide polymorphisms (SNPs) among various TLR genes have been identified among the different human population and their association with susceptibility/resistance to certain infections and other inflammatory diseases. Thus, in the present review the current and future importance of TLRs in immunity, their pattern of expression among various immune cells along with TLR based therapeutic approach is reviewed. TLRs are first described PRRs that revolutionized the biology of host-pathogen interaction and immune response The discovery of different TLRs in humans proved milestone in the field of innate immunity and inflammation The pattern of expression of all the TLRs expressed by human immune cells An association of various TLR SNPs with different inflammatory diseases Currently available drugs or vaccines based on TLRs and their future in drug targeting along with the role in reproduction, and regeneration
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Increased A20-E3 ubiquitin ligase interactions in bid-deficient glia attenuate TLR3- and TLR4-induced inflammation. J Neuroinflammation 2018; 15:130. [PMID: 29720226 PMCID: PMC5930864 DOI: 10.1186/s12974-018-1143-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 04/02/2018] [Indexed: 01/26/2023] Open
Abstract
Background Chronic pro-inflammatory signaling propagates damage to neural tissue and affects the rate of disease progression. Increased activation of Toll-like receptors (TLRs), master regulators of the innate immune response, is implicated in the etiology of several neuropathologies including amyotrophic lateral sclerosis, Alzheimer’s disease, and Parkinson’s disease. Previously, we identified that the Bcl-2 family protein BH3-interacting domain death agonist (Bid) potentiates the TLR4-NF-κB pro-inflammatory response in glia, and specifically characterized an interaction between Bid and TNF receptor associated factor 6 (TRAF6) in microglia in response to TLR4 activation. Methods We assessed the activation of mitogen-activated protein kinase (MAPK) and interferon regulatory factor 3 (IRF3) inflammatory pathways in response to TLR3 and TLR4 agonists in wild-type (wt) and bid-deficient microglia and macrophages, using Western blot and qPCR, focusing on the response of the E3 ubiquitin ligases Pellino 1 (Peli1) and TRAF3 in the absence of microglial and astrocytic Bid. Additionally, by Western blot, we investigated the Bid-dependent turnover of Peli1 and TRAF3 in wt and bid−/− microglia using the proteasome inhibitor Bortezomib. Interactions between the de-ubiquitinating Smad6-A20 and the E3 ubiquitin ligases, TRAF3 and TRAF6, were determined by FLAG pull-down in TRAF6-FLAG or Smad6-FLAG overexpressing wt and bid-deficient mixed glia. Results We elucidated a positive role of Bid in both TIR-domain-containing adapter-inducing interferon-β (TRIF)- and myeloid differentiation primary response 88 (MyD88)-dependent pathways downstream of TLR4, concurrently implicating TLR3-induced inflammation. We identified that Peli1 mRNA levels were significantly reduced in PolyI:C- and lipopolysaccharide (LPS)-stimulated bid-deficient microglia, suggesting disturbed IRF3 activation. Differential regulation of TRAF3 and Peli1, both essential E3 ubiquitin ligases facilitating TRIF-dependent signaling, was observed between wt and bid−/− microglia and astrocytes. bid deficiency resulted in increased A20-E3 ubiquitin ligase protein interactions in glia, specifically A20-TRAF6 and A20-TRAF3, implicating enhanced de-ubiquitination as the mechanism of action by which E3 ligase activity is perturbed. Furthermore, Smad6-facilitated recruitment of the de-ubiquitinase A20 to E3-ligases occurred in a bid-dependent manner. Conclusions This study demonstrates that Bid promotes E3 ubiquitin ligase-mediated signaling downstream of TLR3 and TLR4 and provides further evidence for the potential of Bid inhibition as a therapeutic for the attenuation of the robust pro-inflammatory response culminating in TLR activation. Electronic supplementary material The online version of this article (10.1186/s12974-018-1143-3) contains supplementary material, which is available to authorized users.
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Obesity, Inflammation, Toll-Like Receptor 4 and Fatty Acids. Nutrients 2018; 10:nu10040432. [PMID: 29601492 PMCID: PMC5946217 DOI: 10.3390/nu10040432] [Citation(s) in RCA: 405] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/24/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023] Open
Abstract
Obesity leads to an inflammatory condition that is directly involved in the etiology of cardiovascular diseases, type 2 diabetes mellitus, and certain types of cancer. The classic inflammatory response is an acute reaction to infections or to tissue injuries, and it tends to move towards resolution and homeostasis. However, the inflammatory process that was observed in individuals affected by obesity and metabolic syndrome differs from the classical inflammatory response in certain respects. This inflammatory process manifests itself systemically and it is characterized by a chronic low-intensity reaction. The toll-like receptor 4 (TLR4) signaling pathway is acknowledged as one of the main triggers of the obesity-induced inflammatory response. The aim of the present review is to describe the role that is played by the TLR4 signaling pathway in the inflammatory response and its modulation by saturated and omega-3 polyunsaturated fatty acids. Studies indicate that saturated fatty acids can induce inflammation by activating the TLR4 signaling pathway. Conversely, omega-3 polyunsaturated fatty acids, such as eicosapentaenoic acid and docosahexaenoic acid, exert anti-inflammatory actions through the attenuation of the activation of the TLR4 signaling pathway by either lipopolysaccharides or saturated fatty acids.
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Femenia T, Qian Y, Arentsen T, Forssberg H, Diaz Heijtz R. Toll-like receptor-4 regulates anxiety-like behavior and DARPP-32 phosphorylation. Brain Behav Immun 2018; 69:273-282. [PMID: 29221855 DOI: 10.1016/j.bbi.2017.11.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 12/28/2022] Open
Abstract
Toll-like receptors (TLRs) play a crucial role in early innate immune responses to inflammatory agents and pathogens. In the brain, some members of the TLR family are expressed in glial cells and neurons. In particular, TLR4 has been involved in learning and memory processes, stress-induced adaptations, and pathogenesis of neurodegenerative disorders. However, the role of TLR4 in emotional behaviors and their underlying mechanisms are poorly understood. In this study, we investigated the role of TLR4 in emotional and social behavior by using different behavioral approaches, and assessed potential molecular alterations in important brain areas involved in emotional responses. TLR4 knockout (KO) mice displayed increased anxiety-like behavior and reduced social interaction compared to wild type control mice. This behavioral phenotype was associated with an altered expression of genes known to be involved in emotional behavior [e.g., brain-derived neurotrophic factor (BDNF) and metabotropic glutamate receptors (mGluRs)]. Interestingly, the mRNA expression of dopamine- and cAMP-regulated phosphoprotein-32 (DARPP-32) was strongly upregulated in emotion-related regions of the brain in TLR4 KO mice. In addition, the phosphorylation levels at Thr75 and Ser97 in DARPP-32 were increased in the frontal cortex of TLR4 KO male mice. These findings indicate that TLR4 signaling is involved in emotional regulation through modulation of DARPP-32, which is a signaling hub that plays a critical role in the integration of numerous neurotransmitter systems, including dopamine and glutamate.
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Affiliation(s)
- T Femenia
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
| | - Y Qian
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - T Arentsen
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - H Forssberg
- Department of Women's and Children's Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - R Diaz Heijtz
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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38
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O'Loughlin E, Madore C, Lassmann H, Butovsky O. Microglial Phenotypes and Functions in Multiple Sclerosis. Cold Spring Harb Perspect Med 2018; 8:8/2/a028993. [PMID: 29419406 DOI: 10.1101/cshperspect.a028993] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Microglia are the resident immune cells that constantly survey the central nervous system. They can adapt to their environment and respond to injury or insult by altering their morphology, phenotype, and functions. It has long been debated whether microglial activation is detrimental or beneficial in multiple sclerosis (MS). Recently, the two opposing yet connected roles of microglial activation have been described with the aid of novel microglial markers, RNA profiling, and in vivo models. In this review, microglial phenotypes and functions in the context of MS will be discussed with evidence from both human pathological studies, in vitro and in vivo models. Microglial functional diversity-phagocytosis, antigen presentation, immunomodulation, support, and repair-will also be examined in detail. In addition, this review discusses the emerging evidence for microglia-related targets as biomarkers and therapeutic targets for MS.
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Affiliation(s)
- Elaine O'Loughlin
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Charlotte Madore
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Hans Lassmann
- Center for Brain Research, Medical University of Vienna, A-1090 Vienna, Austria
| | - Oleg Butovsky
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.,Evergrande Center for Immunologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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40
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 899] [Impact Index Per Article: 149.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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41
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Kim GT, Sull JW, Jee SH. Effects of TLR4 Variants on Fasting Glucose Levels in a Korean Population. KOREAN JOURNAL OF CLINICAL LABORATORY SCIENCE 2017. [DOI: 10.15324/kjcls.2017.49.4.345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Gi Tae Kim
- Department of Senior Healthcare, General Graduate School, Eulji University, Seongnam, Korea
| | - Jae Woong Sull
- Department of Senior Healthcare, General Graduate School, Eulji University, Seongnam, Korea
- Depratment of Biomedical Laboratory Science, College of Health Science, Eulji University, Seongnam, Korea
| | - Sun Ha Jee
- Department of Epidemiology and Health Promotion, Institute for Health Promotion, Graduate School of Public Health, Yonsei University, Seoul, Korea
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42
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Affiliation(s)
- Giovanna Traina
- Department of Pharmaceutical Sciences, University of Perugia, Via S. Costanzo, 06126 Perugia, Italy. Tel.: ; Fax: ; E-mail:
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43
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Regulated intramembrane proteolysis: emergent role in cell signalling pathways. Biochem Soc Trans 2017; 45:1185-1202. [PMID: 29079648 DOI: 10.1042/bst20170002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/27/2017] [Accepted: 08/29/2017] [Indexed: 12/12/2022]
Abstract
Receptor signalling events including those initiated following activation of cytokine and growth factor receptors and the well-characterised death receptors (tumour necrosis factor receptor, type 1, FasR and TRAIL-R1/2) are initiated at the cell surface through the recruitment and formation of intracellular multiprotein signalling complexes that activate divergent signalling pathways. Over the past decade, research studies reveal that many of these receptor-initiated signalling events involve the sequential proteolysis of specific receptors by membrane-bound proteases and the γ-secretase protease complexes. Proteolysis enables the liberation of soluble receptor ectodomains and the generation of intracellular receptor cytoplasmic domain fragments. The combined and sequential enzymatic activity has been defined as regulated intramembrane proteolysis and is now a fundamental signal transduction process involved in the termination or propagation of receptor signalling events. In this review, we discuss emerging evidence for a role of the γ-secretase protease complexes and regulated intramembrane proteolysis in cell- and immune-signalling pathways.
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44
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Kelly JR, Minuto C, Cryan JF, Clarke G, Dinan TG. Cross Talk: The Microbiota and Neurodevelopmental Disorders. Front Neurosci 2017; 11:490. [PMID: 28966571 PMCID: PMC5605633 DOI: 10.3389/fnins.2017.00490] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/17/2017] [Indexed: 12/11/2022] Open
Abstract
Humans evolved within a microbial ecosystem resulting in an interlinked physiology. The gut microbiota can signal to the brain via the immune system, the vagus nerve or other host-microbe interactions facilitated by gut hormones, regulation of tryptophan metabolism and microbial metabolites such as short chain fatty acids (SCFA), to influence brain development, function and behavior. Emerging evidence suggests that the gut microbiota may play a role in shaping cognitive networks encompassing emotional and social domains in neurodevelopmental disorders. Drawing upon pre-clinical and clinical evidence, we review the potential role of the gut microbiota in the origins and development of social and emotional domains related to Autism spectrum disorders (ASD) and schizophrenia. Small preliminary clinical studies have demonstrated gut microbiota alterations in both ASD and schizophrenia compared to healthy controls. However, we await the further development of mechanistic insights, together with large scale longitudinal clinical trials, that encompass a systems level dimensional approach, to investigate whether promising pre-clinical and initial clinical findings lead to clinical relevance.
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Affiliation(s)
- John R Kelly
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
| | - Chiara Minuto
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
| | - John F Cryan
- APC Microbiome Institute, University College CorkCork, Ireland.,Department of Anatomy and Neuroscience, University College CorkCork, Ireland
| | - Gerard Clarke
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
| | - Timothy G Dinan
- Department of Psychiatry and Neurobehavioural Science, University College CorkCork, Ireland.,APC Microbiome Institute, University College CorkCork, Ireland
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45
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Caldeira C, Cunha C, Vaz AR, Falcão AS, Barateiro A, Seixas E, Fernandes A, Brites D. Key Aging-Associated Alterations in Primary Microglia Response to Beta-Amyloid Stimulation. Front Aging Neurosci 2017; 9:277. [PMID: 28912710 PMCID: PMC5583148 DOI: 10.3389/fnagi.2017.00277] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 08/03/2017] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by a progressive cognitive decline and believed to be driven by the self-aggregation of amyloid-β (Aβ) peptide into oligomers and fibrils that accumulate as senile plaques. It is widely accepted that microglia-mediated inflammation is a significant contributor to disease pathogenesis; however, different microglia phenotypes were identified along AD progression and excessive Aβ production was shown to dysregulate cell function. As so, the contribution of microglia to AD pathogenesis remains to be elucidated. In this study, we wondered if isolated microglia cultured for 16 days in vitro (DIV) would react differentially from the 2 DIV cells upon treatment with 1000 nM Aβ1-42 for 24 h. No changes in cell viability were observed and morphometric alterations associated to microglia activation, such as volume increase and process shortening, were obvious in 2 DIV microglia, but less evident in 16 DIV cells. These cells showed lower phagocytic, migration and autophagic properties after Aβ treatment than the 2 DIV cultured microglia. Reduced phagocytosis may derive from increased CD33 expression, reduced triggering receptor expressed on myeloid cells 2 (TREM2) and milk fat globule-EGF factor 8 protein (MFG-E8) levels, which were mainly observed in 16 DIV cells. Activation of inflammatory mediators, such as high mobility group box 1 (HMGB1) and pro-inflammatory cytokines, as well as increased expression of Toll-like receptor 2 (TLR2), TLR4 and fractalkine/CX3C chemokine receptor 1 (CX3CR1) cell surface receptors were prominent in 2 DIV microglia, while elevation of matrix metalloproteinase 9 (MMP9) was marked in 16 DIV cells. Increased senescence-associated β-galactosidase (SA-β-gal) and upregulated miR-146a expression that were observed in 16 DIV cells showed to increase by Aβ in 2 DIV microglia. Additionally, Aβ downregulated miR-155 and miR-124, and reduced the CD11b+ subpopulation in 2 DIV microglia, while increased the number of CD86+ cells in 16 DIV microglia. Simultaneous M1 and M2 markers were found after Aβ treatment, but at lower expression in the in vitro aged microglia. Data show key-aging associated responses by microglia when incubated with Aβ, with a loss of reactivity from the 2 DIV to the 16 DIV cells, which course with a reduced phagocytosis, migration and lower expression of inflammatory miRNAs. These findings help to improve our understanding on the heterogeneous responses that microglia can have along the progression of AD disease and imply that therapeutic approaches may differ from early to late stages.
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Affiliation(s)
- Cláudia Caldeira
- Neuron Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
| | - Carolina Cunha
- Neuron Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
| | - Ana R Vaz
- Neuron Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal.,Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
| | - Ana S Falcão
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
| | - Andreia Barateiro
- Neuron Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
| | - Elsa Seixas
- Obesity Laboratory, Instituto Gulbenkian de CiênciaOeiras, Portugal
| | - Adelaide Fernandes
- Neuron Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal.,Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
| | - Dora Brites
- Neuron Glia Biology in Health and Disease, Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal.,Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de LisboaLisbon, Portugal
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46
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Marwarha G, Rostad S, Lilek J, Kleinjan M, Schommer J, Ghribi O. Palmitate Increases β-site AβPP-Cleavage Enzyme 1 Activity and Amyloid-β Genesis by Evoking Endoplasmic Reticulum Stress and Subsequent C/EBP Homologous Protein Activation. J Alzheimers Dis 2017; 57:907-925. [PMID: 28304295 PMCID: PMC5389045 DOI: 10.3233/jad-161130] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Epidemiological studies implicate diets rich in saturated free fatty acids (sFFA) as a potential risk factor for developing Alzheimer's disease (AD). In particular, high plasma levels of the sFFA palmitic acid (palmitate) were shown to inversely correlate with cognitive function. However, the cellular mechanisms by which sFFA may increase the risk for AD are not well known. Endoplasmic reticulum (ER) stress has emerged as one of the signaling pathways initiating and fostering the neurodegenerative changes in AD by increasing the aspartyl protease β-site AβPP cleaving enzyme 1 (BACE1) and amyloid-β (Aβ) genesis. In this study, we determined the extent to which palmitate increases BACE1 and Aβ levels in vitro and in vivo as well as the potential role of ER stress as cellular mechanism underlying palmitate effects. We demonstrate, in palmitate-treated SH-SY5Y neuroblastoma cells and in the hippocampi of palmitate-enriched diet-fed mice, that palmitate evokes the activation of the C/EBP Homologous Protein (CHOP), a transcription factor that is specifically responsive to ER stress. Induction of CHOP expression is associated with increased BACE1 mRNA, protein and activity levels, and subsequent enhanced amyloidogenic processing of amyloid-β protein precursor (AβPP) that culminates in a substantial increase in Aβ genesis. We further show that CHOP is an indispensable molecular mediator of palmitate-induced upregulation in BACE1 activity and Aβ genesis. Indeed, we show that Chop-/- mice and CHOP knocked-down SH-SY5Y neuroblastoma cells do not exhibit the same commensurate degree of palmitate-induced increase in BACE1 expression levels and Aβ genesis.
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Affiliation(s)
| | | | | | | | | | - Othman Ghribi
- Correspondence to: Dr. Othman Ghribi, Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, 1301 North Columbia Road, Grand Forks, North Dakota 58202, USA. Tel.: +1 701 777 2522; Fax: +1 701 777 4490; E-mail:
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47
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Feng PP, Deng P, Liu LH, Ai Q, Yin J, Liu Z, Wang GM. Electroacupuncture Alleviates Postoperative Cognitive Dysfunction in Aged Rats by Inhibiting Hippocampal Neuroinflammation Activated via Microglia/TLRs Pathway. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2017; 2017:6421260. [PMID: 28684969 PMCID: PMC5480055 DOI: 10.1155/2017/6421260] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/18/2017] [Accepted: 04/30/2017] [Indexed: 01/01/2023]
Abstract
Neuroinflammation has been suggested to be involved in the pathogenesis of postoperative cognitive dysfunction (POCD). Electroacupuncture (EA) is an irreplaceable method in traditional Chinese medicine that is used for treating neurodegenerative diseases in clinical and experimental studies. The aim of this study was to examine whether EA improves cognitive dysfunction caused by surgery and to investigate the pathological mechanism of TLR2 and TLR4 in the hippocampus of aged rats. A rat model of POCD was established and treated with EA or minocycline. Both EA- and minocycline-treated rats performed significantly better than untreated operated rats in spatial memory tasks of the Morris water maze (MWM) test, spending comparatively greater amounts of time in the target zone during the probe test. Additionally, decreased levels of proinflammatory cytokines (IL-1β, IL-6, TNF-α, and HMGB1) and decreased TLR2 and TLR4 protein expression in the hippocampus of EA- and minocycline-treated rats were detected. Our data suggested that EA treatment alleviated the cognition performance deficit and neuroinflammation in aged rats following surgery, which may be mediated by inhibiting the expression of hippocampal neuroinflammatory cytokines through the microglia/TLR2/4 pathway.
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Affiliation(s)
- Pei-pei Feng
- Department of Neurobiology & Acupuncture Research, The Third Clinical College, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Pu Deng
- Department of Neurobiology & Acupuncture Research, The Third Clinical College, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Li-hua Liu
- Department of Neurobiology & Acupuncture Research, The Third Clinical College, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Qi Ai
- Department of Neurobiology & Acupuncture Research, The Third Clinical College, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Jie Yin
- Department of Neurobiology & Acupuncture Research, The Third Clinical College, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Zhe Liu
- Department of Neurobiology & Acupuncture Research, The Third Clinical College, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Gai-mei Wang
- Medical Department for Senior Cadres, The Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, China
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48
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Mitterreiter JG, Ouwendijk WJD, van Velzen M, van Nierop GP, Osterhaus ADME, Verjans GMGM. Satellite glial cells in human trigeminal ganglia have a broad expression of functional Toll-like receptors. Eur J Immunol 2017; 47:1181-1187. [PMID: 28508449 DOI: 10.1002/eji.201746989] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 04/04/2017] [Accepted: 05/10/2017] [Indexed: 12/13/2022]
Abstract
Toll-like receptors (TLRs) orchestrate immune responses to a wide variety of danger- and pathogen-associated molecular patterns. Compared to the central nervous system (CNS), expression profile and function of TLRs in the human peripheral nervous system (PNS) are ill-defined. We analyzed TLR expression of satellite glial cells (SGCs) and microglia, glial cells predominantly involved in local immune responses in ganglia of the human PNS and normal-appearing white matter (NAWM) of the CNS, respectively. Ex vivo flow cytometry analysis of cell suspensions obtained from human cadaveric trigeminal ganglia (TG) and NAWM showed that both SGCs and microglia expressed TLR1-5, TLR7, and TLR9, although expression levels varied between these cell types. Immunohistochemistry confirmed expression of TLR1-TLR4 and TLR9 by SGCs in situ. Stimulation of TG- and NAWM-derived cell suspensions with ligands of TLR1-TLR6, but not TLR7 and TLR9, induced interleukin 6 (IL-6) secretion. We identified CD45LOW CD14POS SGCs and microglia, but not CD45HIGH leukocytes and CD45NEG cells as the main source of IL-6 and TNF-α upon stimulation with TLR3 and TLR5 ligands. In conclusion, human TG-resident SGCs express a broad panel of functional TLRs, suggesting their role in initiating and orchestrating inflammation to pathogens in human sensory ganglia.
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Affiliation(s)
- Johanna G Mitterreiter
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, Germany.,Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Monique van Velzen
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Gijsbert P van Nierop
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Albert D M E Osterhaus
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, Germany
| | - Georges M G M Verjans
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, Germany.,Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
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49
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Arnold N, Girke T, Sureshchandra S, Messaoudi I. Acute Simian Varicella Virus Infection Causes Robust and Sustained Changes in Gene Expression in the Sensory Ganglia. J Virol 2016; 90:10823-10843. [PMID: 27681124 PMCID: PMC5110160 DOI: 10.1128/jvi.01272-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/19/2016] [Indexed: 12/13/2022] Open
Abstract
Primary infection with varicella-zoster virus (VZV), a neurotropic alphaherpesvirus, results in varicella. VZV establishes latency in the sensory ganglia and can reactivate later in life to cause herpes zoster. The relationship between VZV and its host during acute infection in the sensory ganglia is not well understood due to limited access to clinical specimens. Intrabronchial inoculation of rhesus macaques with simian varicella virus (SVV) recapitulates the hallmarks of VZV infection in humans. We leveraged this animal model to characterize the host-pathogen interactions in the ganglia during both acute and latent infection by measuring both viral and host transcriptomes on days postinfection (dpi) 3, 7, 10, 14, and 100. SVV DNA and transcripts were detected in sensory ganglia 3 dpi, before the appearance of rash. CD4 and CD8 T cells were also detected in the sensory ganglia 3 dpi. Moreover, lung-resident T cells isolated from the same animals 3 dpi also harbored SVV DNA and transcripts, suggesting that T cells may be responsible for trafficking SVV to the ganglia. Transcriptome sequencing (RNA-Seq) analysis showed that cessation of viral transcription 7 dpi coincides with a robust antiviral innate immune response in the ganglia. Interestingly, a significant number of genes that play a critical role in nervous system development and function remained downregulated into latency. These studies provide novel insights into host-pathogen interactions in the sensory ganglia during acute varicella and demonstrate that SVV infection results in profound and sustained changes in neuronal gene expression. IMPORTANCE Many aspects of VZV infection of sensory ganglia remain poorly understood, due to limited access to human specimens and the fact that VZV is strictly a human virus. Infection of rhesus macaques with simian varicella virus (SVV), a homolog of VZV, provides a robust model of the human disease. Using this model, we show that SVV reaches the ganglia early after infection, most likely by T cells, and that the induction of a robust innate immune response correlates with cessation of virus transcription. We also report significant changes in the expression of genes that play an important role in neuronal function. Importantly, these changes persist long after viral replication ceases. Given the homology between SVV and VZV, and the genetic and physiological similarities between rhesus macaques and humans, our results provide novel insight into the interactions between VZV and its human host and explain some of the neurological consequences of VZV infection.
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Affiliation(s)
- Nicole Arnold
- Graduate Program in Microbiology, University of California-Riverside, Riverside, California, USA
| | - Thomas Girke
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California, USA
| | - Suhas Sureshchandra
- Graduate Program in Genetics, Genomics and Bioinformatics, University of California-Riverside, Riverside, California, USA
| | - Ilhem Messaoudi
- Graduate Program in Microbiology, University of California-Riverside, Riverside, California, USA
- Graduate Program in Genetics, Genomics and Bioinformatics, University of California-Riverside, Riverside, California, USA
- Division of Biomedical Sciences, School of Medicine, University of California-Riverside, Riverside, California, USA
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Ries M, Sastre M. Mechanisms of Aβ Clearance and Degradation by Glial Cells. Front Aging Neurosci 2016; 8:160. [PMID: 27458370 PMCID: PMC4932097 DOI: 10.3389/fnagi.2016.00160] [Citation(s) in RCA: 340] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/17/2016] [Indexed: 12/24/2022] Open
Abstract
Glial cells have a variety of functions in the brain, ranging from immune defense against external and endogenous hazardous stimuli, regulation of synaptic formation, calcium homeostasis, and metabolic support for neurons. Their dysregulation can contribute to the development of neurodegenerative disorders, including Alzheimer’s disease (AD). One of the most important functions of glial cells in AD is the regulation of Amyloid-β (Aβ) levels in the brain. Microglia and astrocytes have been reported to play a central role as moderators of Aβ clearance and degradation. The mechanisms of Aβ degradation by glial cells include the production of proteases, including neprilysin, the insulin degrading enzyme, and the endothelin-converting enzymes, able to hydrolyse Aβ at different cleavage sites. Besides these enzymes, other proteases have been described to have some role in Aβ elimination, such as plasminogen activators, angiotensin-converting enzyme, and matrix metalloproteinases. Other relevant mediators that are released by glial cells are extracellular chaperones, involved in the clearance of Aβ alone or in association with receptors/transporters that facilitate their exit to the blood circulation. These include apolipoproteins, α2macroglobulin, and α1-antichymotrypsin. Finally, astrocytes and microglia have an essential role in phagocytosing Aβ, in many cases via a number of receptors that are expressed on their surface. In this review, we examine all of these mechanisms, providing an update on the latest research in this field.
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Affiliation(s)
- Miriam Ries
- Division of Brain Sciences, Imperial College London, Hammersmith Hospital London, UK
| | - Magdalena Sastre
- Division of Brain Sciences, Imperial College London, Hammersmith Hospital London, UK
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