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Haque I, Thapa P, Burns DM, Zhou J, Sharma M, Sharma R, Singh V. NLRP3 Inflammasome Inhibitors for Antiepileptogenic Drug Discovery and Development. Int J Mol Sci 2024; 25:6078. [PMID: 38892264 PMCID: PMC11172514 DOI: 10.3390/ijms25116078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
Epilepsy is one of the most prevalent and serious brain disorders and affects over 70 million people globally. Antiseizure medications (ASMs) relieve symptoms and prevent the occurrence of future seizures in epileptic patients but have a limited effect on epileptogenesis. Addressing the multifaceted nature of epileptogenesis and its association with the Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated neuroinflammation requires a comprehensive understanding of the underlying mechanisms of these medications for the development of targeted therapeutic strategies beyond conventional antiseizure treatments. Several types of NLRP3 inhibitors have been developed and their effect has been validated both in in vitro and in vivo models of epileptogenesis. In this review, we discuss the advances in understanding the regulatory mechanisms of NLRP3 activation as well as progress made, and challenges faced in the development of NLRP3 inhibitors for the treatment of epilepsy.
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Affiliation(s)
- Inamul Haque
- Research and Development Service, Kansas City Veterans Affairs Medical Center, Kansas City, MO 64128, USA; (P.T.); (D.M.B.); (M.S.); (R.S.)
- Department of Math, Science and Business Technology, Kansas City Kansas Community College, Kansas City, KS 66112, USA
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Pritam Thapa
- Research and Development Service, Kansas City Veterans Affairs Medical Center, Kansas City, MO 64128, USA; (P.T.); (D.M.B.); (M.S.); (R.S.)
- Drug Discovery Program, Midwest Veterans’ Biomedical Research Foundation, KCVA Medical Center, Kansas City, MO 64128, USA
| | - Douglas M. Burns
- Research and Development Service, Kansas City Veterans Affairs Medical Center, Kansas City, MO 64128, USA; (P.T.); (D.M.B.); (M.S.); (R.S.)
| | - Jianping Zhou
- Renal Research Laboratory, Kansas City VA Medical Center, Kansas City, MO 64128, USA;
| | - Mukut Sharma
- Research and Development Service, Kansas City Veterans Affairs Medical Center, Kansas City, MO 64128, USA; (P.T.); (D.M.B.); (M.S.); (R.S.)
- Drug Discovery Program, Midwest Veterans’ Biomedical Research Foundation, KCVA Medical Center, Kansas City, MO 64128, USA
- Renal Research Laboratory, Kansas City VA Medical Center, Kansas City, MO 64128, USA;
| | - Ram Sharma
- Research and Development Service, Kansas City Veterans Affairs Medical Center, Kansas City, MO 64128, USA; (P.T.); (D.M.B.); (M.S.); (R.S.)
| | - Vikas Singh
- Research and Development Service, Kansas City Veterans Affairs Medical Center, Kansas City, MO 64128, USA; (P.T.); (D.M.B.); (M.S.); (R.S.)
- Drug Discovery Program, Midwest Veterans’ Biomedical Research Foundation, KCVA Medical Center, Kansas City, MO 64128, USA
- Division of Neurology, Kansas City VA Medical Center, Kansas City, MO 64128, USA
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2
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Quick JD, Silva C, Wong JH, Lim KL, Reynolds R, Barron AM, Zeng J, Lo CH. Lysosomal acidification dysfunction in microglia: an emerging pathogenic mechanism of neuroinflammation and neurodegeneration. J Neuroinflammation 2023; 20:185. [PMID: 37543564 PMCID: PMC10403868 DOI: 10.1186/s12974-023-02866-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 07/30/2023] [Indexed: 08/07/2023] Open
Abstract
Microglia are the resident innate immune cells in the brain with a major role in orchestrating immune responses. They also provide a frontline of host defense in the central nervous system (CNS) through their active phagocytic capability. Being a professional phagocyte, microglia participate in phagocytic and autophagic clearance of cellular waste and debris as well as toxic protein aggregates, which relies on optimal lysosomal acidification and function. Defective microglial lysosomal acidification leads to impaired phagocytic and autophagic functions which result in the perpetuation of neuroinflammation and progression of neurodegeneration. Reacidification of impaired lysosomes in microglia has been shown to reverse neurodegenerative pathology in Alzheimer's disease. In this review, we summarize key factors and mechanisms contributing to lysosomal acidification impairment and the associated phagocytic and autophagic dysfunction in microglia, and how these defects contribute to neuroinflammation and neurodegeneration. We further discuss techniques to monitor lysosomal pH and therapeutic agents that can reacidify impaired lysosomes in microglia under disease conditions. Finally, we propose future directions to investigate the role of microglial lysosomal acidification in lysosome-mitochondria crosstalk and in neuron-glia interaction for more comprehensive understanding of its broader CNS physiological and pathological implications.
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Affiliation(s)
- Joseph D Quick
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Cristian Silva
- Faculty of Graduate Studies, University of Kelaniya, Kelaniya, Sri Lanka
| | - Jia Hui Wong
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Kah Leong Lim
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Richard Reynolds
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Anna M Barron
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jialiu Zeng
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
| | - Chih Hung Lo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
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Nagar A, Bharadwaj R, Shaikh MOF, Roy A. What are NLRP3-ASC specks? an experimental progress of 22 years of inflammasome research. Front Immunol 2023; 14:1188864. [PMID: 37564644 PMCID: PMC10411722 DOI: 10.3389/fimmu.2023.1188864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/12/2023] [Indexed: 08/12/2023] Open
Abstract
Speck assembly is the hallmark of NLRP3 inflammasome activation. The 1µm structure comprising of NLRP3 and ASC is the first observable phenotype of NLRP3 activation. While the common consensus is that the specks are the site of inflammasome activity, no direct experimental evidence exists to support this notion. In these 22 years, since the inflammasome discovery, several research studies have been published which directly or indirectly support or refute the idea of speck being the inflammasome. This review compiles the data from two decades of research to answer a long-standing question: "What are NLRP3-ASC specks?"
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Affiliation(s)
- Abhinit Nagar
- Department of Flow Cytometry, Cytek Biosciences, Fremont, CA, United States
| | - Ravi Bharadwaj
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, United States
| | - Mohammad Omar Faruk Shaikh
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA, United States
- Department of Anesthesia, Harvard Medical School, Boston, MA, United States
| | - Abhishek Roy
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
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Hu Z, Xuan L, Wu T, Jiang N, Liu X, Chang J, Wang T, Han N, Tian X. Taxifolin attenuates neuroinflammation and microglial pyroptosis via the PI3K/Akt signaling pathway after spinal cord injury. Int Immunopharmacol 2023; 114:109616. [PMID: 36700780 DOI: 10.1016/j.intimp.2022.109616] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 12/14/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Spinal cord injury (SCI) is a severe injury characterized by neuroinflammation and oxidative stress. Taxifolin is exhibits anti-inflammatory and antioxidative activities in neurologic diseases. However, the roles and mechanisms of taxifolin in neuroinflammation and microglial pyroptosis after SCI remain unclear. The present study aims to investigate the effect of taxifolin on SCI and its potential underlying mechanisms in in vivo and in vitro models. In this study, taxifolin markedly reduced microglial activation mediated oxidative stress, and inhibited the expression of pyroptosis-related proteins (NLRP3, GSDMD, ASC, and Caspase-1) and inflammatory cytokines (IL-1β and IL-18) after SCI, as shown by immunofluorescence staining and western blot assays. In addition, taxifolin promoted axonal regeneration and improved functional recovery after SCI. In vitro studies showed that taxifolin attenuated the activation of microglia and oxidative stress after lipopolysaccharide (LPS) + adenosine-triphosphate (ATP) stimulation in BV2 cells. We also observed that taxifolin inhibited the pyroptosis-related proteins and reduced the release of inflammatory cytokines. Moreover, to explore how taxifolin exerts its effects on microglial pyroptosis and axonal regeneration of neurons, we performed an in vitro study in BV-2 cells and PC12 cells co-culture. The results revealed that taxifolin facilitated axonal regeneration of PC12 cells in co-culture with LPS + ATP-induced BV-2 cells. Mechanistically, taxifolin regulated microglial pyroptosis via the PI3K/AKT signaling pathway. Taken together, these results suggest that taxifolin alleviates neuroinflammation and microglial pyroptosis through the PI3K/AKT signaling pathway after SCI, and promotes axonal regeneration and improves functional recovery, suggesting that taxifolin may represent a potential therapeutic agent for SCI.
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Affiliation(s)
- Zhenxin Hu
- Department of Orthopedics, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, China
| | - Lina Xuan
- Department of Neurosurgery, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, China
| | - Tingting Wu
- The First Clinical Medical Colloge, Wenzhou Medical University, Wenzhou 325035, China
| | - Nizhou Jiang
- Department of Orthopedics, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, China
| | - Xiangjun Liu
- Department of Oncology, The Second Affiliated Hospital of Dalian Medical University, Dalian 116027, China
| | - Jiazhen Chang
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian 116044, China
| | - Te Wang
- Department of Orthopedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325088, China
| | - Nan Han
- Department of Ultrasonography, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, China.
| | - Xiliang Tian
- Department of Orthopedics, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, China.
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Hu X, Zhang Y, Wang L, Ding J, Li M, Li H, Wu L, Zeng Z, Xia H. Microglial activation in the motor cortex mediated NLRP3-related neuroinflammation and neuronal damage following spinal cord injury. Front Cell Neurosci 2022; 16:956079. [PMID: 36339822 PMCID: PMC9630363 DOI: 10.3389/fncel.2022.956079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 07/27/2022] [Indexed: 12/30/2023] Open
Abstract
Spinal cord injury (SCI) is a traumatic event that can lead to neurodegeneration. Neuronal damage in the primary motor cortex (M1) can hinder motor function recovery after SCI. However, the exact mechanisms involved in neuronal damage after SCI remain incompletely understood. In this study, we found that microglia were activated in M1 after SCI, which triggered Nod-like receptor protein 3 (NLRP3) related chronic neuroinflammation and neuronal damage in vivo. Meanwhile, treatment with the microglia inhibitor minocycline reduced inflammation-induced neuronal damage in M1, protected the integrity of the motor conduction pathway, and promoted motor function recovery. Furthermore, we simulated chronic inflammation in M1 after SCI by culturing the primary neurons in primary microglia-conditioned medium, and observed that the injury to the primary neurons also occurred in vitro; however, as observed in vivo, these effects could be mitigated by minocycline treatment. Our results indicated that microglial activation in M1 mediates NLRP3-related neuroinflammation and causes the injury to M1 neurons, thereby impairing the integrity of the motor conduction pathway and inhibiting motor function recovery. These findings might contribute to the identification of novel therapeutic strategies for SCI.
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Affiliation(s)
- Xvlei Hu
- Department of Neurosurgery, Shanxi Provincial People's Hospital, Taiyuan, China
- School of Clinical Medicine, Ningxia Medical University, Yinchuan, China
- Ningxia Key Laboratory of Craniocerebral Diseases, Ningxia Medical University, Yinchuan, China
| | - Yifan Zhang
- School of Clinical Medicine, Ningxia Medical University, Yinchuan, China
- Ningxia Human Stem Cell Research Institute, General Hospital of Ningxia Medical University, Yinchuan, China
| | - Lei Wang
- Department of Neurosurgery, Henan Provincial People's Hospital, Zhengzhou, China
| | - Jiangwei Ding
- Ningxia Key Laboratory of Craniocerebral Diseases, Ningxia Medical University, Yinchuan, China
| | - Mei Li
- School of Clinical Medicine, Ningxia Medical University, Yinchuan, China
- Ningxia Key Laboratory of Craniocerebral Diseases, Ningxia Medical University, Yinchuan, China
| | - Hailiang Li
- Ningxia Key Laboratory of Craniocerebral Diseases, Ningxia Medical University, Yinchuan, China
| | - Liang Wu
- Department of Neurosurgery, General Hospital of Ningxia Medical University, Yinchuan, China
| | - Zhong Zeng
- School of Clinical Medicine, Ningxia Medical University, Yinchuan, China
- Ningxia Key Laboratory of Craniocerebral Diseases, Ningxia Medical University, Yinchuan, China
| | - Hechun Xia
- Ningxia Human Stem Cell Research Institute, General Hospital of Ningxia Medical University, Yinchuan, China
- Department of Neurosurgery, General Hospital of Ningxia Medical University, Yinchuan, China
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6
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Xu Q, Zhao B, Ye Y, Li Y, Zhang Y, Xiong X, Gu L. Relevant mediators involved in and therapies targeting the inflammatory response induced by activation of the NLRP3 inflammasome in ischemic stroke. J Neuroinflammation 2021; 18:123. [PMID: 34059091 PMCID: PMC8166383 DOI: 10.1186/s12974-021-02137-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/24/2021] [Indexed: 12/14/2022] Open
Abstract
The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome is a member of the NLR family of inherent immune cell sensors. The NLRP3 inflammasome can detect tissue damage and pathogen invasion through innate immune cell sensor components commonly known as pattern recognition receptors (PRRs). PRRs promote activation of nuclear factor kappa B (NF-κB) pathways and the mitogen-activated protein kinase (MAPK) pathway, thus increasing the transcription of genes encoding proteins related to the NLRP3 inflammasome. The NLRP3 inflammasome is a complex with multiple components, including an NAIP, CIITA, HET-E, and TP1 (NACHT) domain; apoptosis-associated speck-like protein containing a CARD (ASC); and a leucine-rich repeat (LRR) domain. After ischemic stroke, the NLRP3 inflammasome can produce numerous proinflammatory cytokines, mediating nerve cell dysfunction and brain edema and ultimately leading to nerve cell death once activated. Ischemic stroke is a disease with high rates of mortality and disability worldwide and is being observed in increasingly younger populations. To date, there are no clearly effective therapeutic strategies for the clinical treatment of ischemic stroke. Understanding the NLRP3 inflammasome may provide novel ideas and approaches because targeting of upstream and downstream molecules in the NLRP3 pathway shows promise for ischemic stroke therapy. In this manuscript, we summarize the existing evidence regarding the composition and activation of the NLRP3 inflammasome, the molecules involved in inflammatory pathways, and corresponding drugs or molecules that exert effects after cerebral ischemia. This evidence may provide possible targets or new strategies for ischemic stroke therapy.
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Affiliation(s)
- Qingxue Xu
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Bo Zhao
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Yingze Ye
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Yina Li
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Yonggang Zhang
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Xiaoxing Xiong
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
- Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
| | - Lijuan Gu
- Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
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Stahl-Meyer J, Stahl-Meyer K, Jäättelä M. Control of mitosis, inflammation, and cell motility by limited leakage of lysosomes. Curr Opin Cell Biol 2021; 71:29-37. [PMID: 33684809 DOI: 10.1016/j.ceb.2021.02.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 02/07/2023]
Abstract
Lysosomal membrane permeabilization and subsequent leakage of lysosomal hydrolases into the cytosol are considered as the major hallmarks of evolutionarily conserved lysosome-dependent cell death. Contradicting this postulate, new sensitive methods that can detect a minimal lysosomal membrane damage have demonstrated that lysosomal leakage does not necessarily equal cell death. Notably, cells are not only able to survive minor lysosomal membrane permeabilization, but some of their normal functions actually depend on leaked lysosomal hydrolases. Here we discuss emerging data suggesting that spatially and temporally controlled lysosomal leakage delivers lysosomal hydrolases to specific subcellular sites of action and controls at least three essential cellular processes, namely mitotic chromosome segregation, inflammatory signaling, and cellular motility.
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Affiliation(s)
- Jonathan Stahl-Meyer
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Kamilla Stahl-Meyer
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, Copenhagen, Denmark; Orphazyme A/S, Copenhagen, Denmark
| | - Marja Jäättelä
- Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center, Copenhagen, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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Nagakannan P, Tabeshmehr P, Eftekharpour E. Oxidative damage of lysosomes in regulated cell death systems: Pathophysiology and pharmacologic interventions. Free Radic Biol Med 2020; 157:94-127. [PMID: 32259579 DOI: 10.1016/j.freeradbiomed.2020.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/31/2020] [Accepted: 04/01/2020] [Indexed: 12/16/2022]
Abstract
Lysosomes are small specialized organelles containing a variety of different hydrolase enzymes that are responsible for degradation of all macromolecules, entering the cells through the endosomal system or originated from the internal sources. This allows for transport and recycling of nutrients and internalization of surface proteins for antigen presentation as well as maintaining cellular homeostasis. Lysosomes are also important storage compartments for metal ions and nutrients. The integrity of lysosomal membrane is central to maintaining their normal function, but like other cellular membranes, lysosomal membrane is subject to damage mediated by reactive oxygen species. This results in spillage of lysosomal enzymes into the cytoplasm, leading to proteolytic damage to cellular systems and organelles. Several forms of lysosomal dependent cell death have been identified in diseases. Examination of these events are important for finding treatment strategies relevant to cancer or neurodegenerative diseases as well as autoimmune deficiencies. In this review, we have examined the current literature on involvement of lysosomes in induction of programed cell death and have provided an extensive list of therapeutic approaches that can modulate cell death. Exploitation of these mechanisms can lead to novel therapies for cancer and neurodegenerative diseases.
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Affiliation(s)
- Pandian Nagakannan
- Regenerative Medicine Program and Spinal Cord Research Centre, Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Parisa Tabeshmehr
- Regenerative Medicine Program and Spinal Cord Research Centre, Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Eftekhar Eftekharpour
- Regenerative Medicine Program and Spinal Cord Research Centre, Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada.
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Experimental Study Using Multiple Strains of Prion Disease in Cattle Reveals an Inverse Relationship between Incubation Time and Misfolded Prion Accumulation, Neuroinflammation, and Autophagy. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1461-1473. [PMID: 32259521 DOI: 10.1016/j.ajpath.2020.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/11/2020] [Accepted: 03/20/2020] [Indexed: 02/07/2023]
Abstract
Proteinopathies result from aberrant folding and accumulation of specific proteins. Currently, there is a lack of knowledge about the factors that influence disease progression, making this a key challenge for the development of therapies for proteinopathies. Because of the similarities between transmissible spongiform encephalopathies (TSEs) and other protein misfolding diseases, TSEs can be used to understand other proteinopathies. Bovine spongiform encephalopathy (BSE) is a TSE that occurs in cattle and can be subdivided into three strains: classic BSE and atypical BSEs (H and L types) that have shorter incubation periods. The NACHT, LRR, and PYD domains-containing protein 3 inflammasome is a critical component of the innate immune system that leads to release of IL-1β. Macroautophagy is an intracellular mechanism that plays an essential role in protein clearance. In this study, the retina was used as a model to investigate the relationship between disease incubation period, prion protein accumulation, neuroinflammation, and changes in macroautophagy. We demonstrate that atypical BSEs present with increased prion protein accumulation, neuroinflammation, and decreased autophagy. This work suggests a relationship between disease time course, neuroinflammation, and the autophagic stress response, and may help identify novel therapeutic biomarkers that can delay or prevent the progression of proteinopathies.
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Schölwer I, Habib P, Voelz C, Rolfes L, Beyer C, Slowik A. NLRP3 Depletion Fails to Mitigate Inflammation but Restores Diminished Phagocytosis in BV-2 Cells After In Vitro Hypoxia. Mol Neurobiol 2020; 57:2588-2599. [PMID: 32239449 DOI: 10.1007/s12035-020-01909-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 03/23/2020] [Indexed: 12/30/2022]
Abstract
Post-hypoxic/ischemic neuroinflammation is selectively driven by sterile inflammation, which implies the interplay of brain-intrinsic immune cells with other neural cells and immigrated peripheral immune cells. The resultant inflammatory cascade evolves extra- and intracellular pathogen and danger-associated receptors. The latter interacts with multiprotein complexes termed inflammasomes. The NLRP3 inflammasome is one of the best-described inflammasomes. However, its impact on post-ischemic neuroinflammation and its role in neuroprotection after ischemic stroke are still under debate. Microglial cells are known to be the main source of neuroinflammation; hence, we depleted NLRP3 in BV-2 microglial cells using shRNA to investigate its role in IL-1β maturation and phagocytosis after hypoxia (oxygen-glucose-deprivation (OGD)). We also examined the expression profiles of other inflammasomes (NLRC4, AIM2, ASC) and caspase-1 activity after OGD. OGD triggered caspase-1 activity and increased IL-1β secretion in BV-2 cells with no alteration after NLRP3 depletion. The expression of the AIM2 inflammasome was significantly higher after OGD in NLRP3-depleted cells, whereas NLRC4 was unaltered in all groups. Interestingly, OGD induced a complete inactivation of phagocytic activity in wild-type cells, while in NLRP3-depleted BV-2, this inactivity was restored after hypoxia. Our findings indicate a minor role of NLRP3 in the inflammatory response after hypoxic/ischemic stimulus. However, NLRP3 seems to play a pivotal role in the regulation of post-ischemic phagocytosis. This might be a prerequisite for the putative neuroprotective effect.
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Affiliation(s)
- Isabelle Schölwer
- Institute of Neuroanatomy, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Pardes Habib
- Department of Neurology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Clara Voelz
- Institute of Neuroanatomy, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Leoni Rolfes
- Neurology Clinic and Institute for Translational Neurology, University of Muenster, Münster, Germany
| | - Cordian Beyer
- Institute of Neuroanatomy, Medical Faculty, RWTH Aachen University, Aachen, Germany
- JARA-Brain, RWTH Aachen University, Aachen, Germany
| | - Alexander Slowik
- Institute of Neuroanatomy, Medical Faculty, RWTH Aachen University, Aachen, Germany.
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11
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Recent advances in the mechanisms of NLRP3 inflammasome activation and its inhibitors. Cell Death Dis 2019; 10:128. [PMID: 30755589 PMCID: PMC6372664 DOI: 10.1038/s41419-019-1413-8] [Citation(s) in RCA: 771] [Impact Index Per Article: 154.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/27/2019] [Accepted: 01/28/2019] [Indexed: 12/14/2022]
Abstract
The NLRP3 inflammasome is a multimeric protein complex that initiates an inflammatory form of cell death and triggers the release of proinflammatory cytokines IL-1β and IL-18. The NLRP3 inflammasome has been implicated in a wide range of diseases, including Alzheimer’s disease, Prion diseases, type 2 diabetes, and some infectious diseases. It has been found that a variety of stimuli including danger-associated molecular patterns (DAMPs, such as silica and uric acid crystals) and pathogen-associated molecular patterns (PAMPs) can activate NLRP3 inflammasome, but the specific regulatory mechanisms of NLRP3 inflammasome activation remain unclear. Understanding the mechanisms of NLRP3 activation will enable the development of its specific inhibitors to treat NLRP3-related diseases. In this review, we summarize current understanding of the regulatory mechanisms of NLRP3 inflammasome activation as well as inhibitors that specifically and directly target NLRP3.
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12
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Celastrol inhibits microglial pyroptosis and attenuates inflammatory reaction in acute spinal cord injury rats. Int Immunopharmacol 2018; 66:215-223. [PMID: 30472522 DOI: 10.1016/j.intimp.2018.11.029] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/15/2018] [Accepted: 11/16/2018] [Indexed: 12/18/2022]
Abstract
Pyroptosis pathway is closely related to inflammation. However, Celastrol effect on pyroptosis pathway after spinal cord injury (SCI) are poorly understood. We studied the anti-inflammatory and neuroprotective effects of Celastrol on acute spinal cord injury in rats, and its anti-inflammatory effects on lipopolysaccharide (LPS)/ATP-induced microgliosis. Our results show that Celastrol can improve the recovery of hindlimb motor function after SCI in Sprague-Dawley (SD) rats, and reduce the cavity area of spinal cord injury along with the neuronal loss. Celastrol simultaneously reduced the activation of microglia (especially M1 microglia) in the spinal cord, inhibited the pyroptosis-related proteins (NLRP3 ASC Caspase-1 GSDMD), reduced the release of TNF-α IL-1β and IL-18 inflammatory factors, and increased the release of IL10 cytokines. In vitro studies showed that Celastrol reduced the toxicity resulting from the administration of LPS with ATP to BV-2 cells, inhibited the pyroptosis-related proteins (NLRP3 Caspase-1 GSDMD), and inhibited the release of corresponding inflammatory factors. Finally, Celastrol can inhibit the expression of NFκB/p-p65 in vitro and in vivo. Our results show that Celastrol can attenuate the inflammatory response of the spinal cord after SCI, which is associated with inhibition of microglial activation and pyroptosis pathway. Further study to explore the use of Celastrol to treat SCI is warranted.
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Lai M, Yao H, Shah SZA, Wu W, Wang D, Zhao Y, Wang L, Zhou X, Zhao D, Yang L. The NLRP3-Caspase 1 Inflammasome Negatively Regulates Autophagy via TLR4-TRIF in Prion Peptide-Infected Microglia. Front Aging Neurosci 2018; 10:116. [PMID: 29720937 PMCID: PMC5915529 DOI: 10.3389/fnagi.2018.00116] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 04/03/2018] [Indexed: 12/15/2022] Open
Abstract
Prion diseases are neurodegenerative disorders characterized by the accumulation of misfolded prion protein, spongiform changes in the brain, and brain inflammation as a result of the wide-spread activation of microglia. Autophagy is a highly conserved catabolic process for the clearance of cytoplasmic components, including protein aggregates and damaged organelles; this process also eliminates pathological PrPSc as it accumulates during prion infection. The NALP3 inflammasome is a multiprotein complex that is a component of the innate immune system and is responsible for the release of pro-inflammatory cytokines. Our previous study showed that the neurotoxic prion peptide PrP106-126 induces NALP3 inflammasome activation and subsequent IL-1β release in microglia. Autophagy is involved in the regulation of the immune responses and inflammation in many diseases including neurodegenerative diseases. However, the relationship between autophagy and NALP3 inflammasome in prion diseases has not been investigated. In this study, we demonstrated that the processing and release of mature IL-1β is significantly enhanced by the inhibition of autophagy. Conversely, gene-silencing of the NALP3 inflammasome promotes autophagy. Suppression of TRIF or TLR4 by siRNA attenuated PrP106-126-induced autophagy, which is indicating that the TLR4-TRIF signaling pathway is involved in PrP106-26-induced autophagy. Caspase 1 directly cleaved TRIF to diminish TLR-4-TRIF mediated autophagy. Our findings suggest that the inhibition of autophagy by NALP3 inflammasome is probably mediated by activated Caspase-1-induced TRIF cleavage. This is the first study reporting that the NALP3 inflammasome complex negatively regulates autophagy in response to PrP106-126 stimulation in microglia, and partly explains the mechanism of autophagy inhibition by Caspase-1 in PrP106-126-induced BV2 cell activation. Our findings suggest that autophagy up-regulation and inhibition of Caspase-1 may protect against prion-induced neuroinflammation and accelerate misfolded protein degradation and are potential therapeutic approaches for prion diseases.
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Affiliation(s)
- Mengyu Lai
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Hao Yao
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Syed Zahid Ali Shah
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Wei Wu
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Di Wang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Ying Zhao
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Lu Wang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Xiangmei Zhou
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Deming Zhao
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
| | - Lifeng Yang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, State Key Laboratories for Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, China Agricultural University, Beijing, China
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Shao QH, Zhang XL, Yang PF, Yuan YH, Chen NH. Amyloidogenic proteins associated with neurodegenerative diseases activate the NLRP3 inflammasome. Int Immunopharmacol 2017; 49:155-160. [PMID: 28595078 DOI: 10.1016/j.intimp.2017.05.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/12/2017] [Accepted: 05/22/2017] [Indexed: 10/19/2022]
Abstract
Neuroinflammation has been shown as an essential factor in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease, and Multiple Sclerosis. Furthermore, activated microglia and increased pro-inflammatory cytokines are the major hallmarks in neurodegenerative diseases. A multimolecular complex named as inflammasome is involved in the process of inflammatory response, which can activate inflammatory caspases, leading to the cleavage and secretion of inflammatory cytokines, and finally generates a potent inflammatory response. In neurodegenerative diseases, it has been widely assumed that some types of amyloid proteins might be the triggers to activate the NLRP3 inflammasome. In this review, we summarize the current researches about the role of NLRP3 inflammasome, by reviewing the main studies in vitro and in vivo experiments and discuss the potential for new therapeutic interventions in neurodegenerative diseases.
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Affiliation(s)
- Qian-Hang Shao
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xiao-Ling Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Peng-Fei Yang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Yu-He Yuan
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China; College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China.
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15
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Pascua-Maestro R, Diez-Hermano S, Lillo C, Ganfornina MD, Sanchez D. Protecting cells by protecting their vulnerable lysosomes: Identification of a new mechanism for preserving lysosomal functional integrity upon oxidative stress. PLoS Genet 2017; 13:e1006603. [PMID: 28182653 PMCID: PMC5325589 DOI: 10.1371/journal.pgen.1006603] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/24/2017] [Accepted: 01/24/2017] [Indexed: 12/31/2022] Open
Abstract
Environmental insults such as oxidative stress can damage cell membranes. Lysosomes are particularly sensitive to membrane permeabilization since their function depends on intraluminal acidic pH and requires stable membrane-dependent proton gradients. Among the catalog of oxidative stress-responsive genes is the Lipocalin Apolipoprotein D (ApoD), an extracellular lipid binding protein endowed with antioxidant capacity. Within the nervous system, cell types in the defense frontline, such as astrocytes, secrete ApoD to help neurons cope with the challenge. The protecting role of ApoD is known from cellular to organism level, and many of its downstream effects, including optimization of autophagy upon neurodegeneration, have been described. However, we still cannot assign a cellular mechanism to ApoD gene that explains how this protection is accomplished. Here we perform a comprehensive analysis of ApoD intracellular traffic and demonstrate its role in lysosomal pH homeostasis upon paraquat-induced oxidative stress. By combining single-lysosome in vivo pH measurements with immunodetection, we demonstrate that ApoD is endocytosed and targeted to a subset of vulnerable lysosomes in a stress-dependent manner. ApoD is functionally stable in this acidic environment, and its presence is sufficient and necessary for lysosomes to recover from oxidation-induced alkalinization, both in astrocytes and neurons. This function is accomplished by preventing lysosomal membrane permeabilization. Two lysosomal-dependent biological processes, myelin phagocytosis by astrocytes and optimization of neurodegeneration-triggered autophagy in a Drosophila in vivo model, require ApoD-related Lipocalins. Our results uncover a previously unknown biological function of ApoD, member of the finely regulated and evolutionary conserved gene family of extracellular Lipocalins. They set a lipoprotein-mediated regulation of lysosomal membrane integrity as a new mechanism at the hub of many cellular functions, critical for the outcome of a wide variety of neurodegenerative diseases. These results open therapeutic opportunities by providing a route of entry and a repair mechanism for lysosomes in pathological situations. This work is the result of our search for the mechanism of action of Apolipoprotein D (ApoD), a neuroprotective lipid-binding protein that confers cell resistance to oxidative stress. ApoD is one of the few genes consistently over-expressed in the aging brain of all vertebrate species, and no nervous system disease has been found concurring without ApoD over-expression. All evidence supports ApoD as an endogenous mechanism of protection. We demonstrate here that this extracellular lipid binding protein is endocytosed and targeted in a finely controlled way to subsets of lysosomes in need of protection, those most sensitive to oxidative stress. ApoD reveals the existence of biologically relevant lysosomal heterogeneity that conditions the oxidation state of cells, their phagocytic or autophagic capacity, and the final output in neurodegenerative conditions. The stable presence of ApoD in lysosomes is sufficient and necessary for lysosomes to recover from oxidation-induced membrane permeabilization and loss of proton gradients. ApoD-mediated control of lysosomal membrane integrity represents a new cell-protection mechanism at the hub of many cellular functions, and is critical for the outcome of a wide variety of neurodegenerative diseases. Therapeutic opportunities open, by providing a route of entry and a repair mechanism for lysosomes in pathological situations.
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Affiliation(s)
- Raquel Pascua-Maestro
- Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, Valladolid, Spain
| | - Sergio Diez-Hermano
- Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, Valladolid, Spain
| | - Concepción Lillo
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
| | - Maria D. Ganfornina
- Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, Valladolid, Spain
- * E-mail: (MDG); (DS)
| | - Diego Sanchez
- Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, Valladolid, Spain
- * E-mail: (MDG); (DS)
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16
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Pennisi M, Crupi R, Di Paola R, Ontario ML, Bella R, Calabrese EJ, Crea R, Cuzzocrea S, Calabrese V. Inflammasomes, hormesis, and antioxidants in neuroinflammation: Role of NRLP3 in Alzheimer disease. J Neurosci Res 2016; 95:1360-1372. [PMID: 27862176 DOI: 10.1002/jnr.23986] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 10/17/2016] [Indexed: 12/31/2022]
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disorder leading to cognitive decline, neuropsychiatric symptoms, disability, caregiver burden, and premature death. It represents the most prevalent cause of dementia, and its incidence rates exponentially increase with increasing age. The number of Americans living with AD is rapidly increasing. An estimated 5.4 million Americans of all ages have AD in 2016. One in nine people aged 65 and older has AD, and by midcentury, someone in the United States will develop the disease every 33 sec. It is now accepted that neuroinflammation is a common feature of neurological disease. Inflammasomes, which are a multiprotein complex part of the innate immune system, induce inflammation in response to various stimuli, such as pathogens and stress. Inflammasomes activate proinflammatory caspases, such as caspase-1, leading to the activation of the proinflammatory cytokines interleukin (IL)-1b, IL-18, and IL-33, which promote neuroinflammation and brain pathologies. The nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing-3 (NLRP3) inflammasome is the best characterized in neurodegenerative diseases, in particular AD. Recent research suggests that NLRP3 could possibly be used in targeted therapies to alleviate neuroinflammation. Modulation of endogenous cellular defense mechanisms may be an innovative approach to therapeutic intervention in AD and other disorders associated with neuroinflammation and neurodegeneration. Herein, we introduce the hormetic dose-response concept and present possible mechanisms and applications to neuroprotection. We summarize the mechanisms involved in activation of the NLRP3 inflammasome and its role in neuroinflammation. We also address and propose the potential therapeutic utility of the nutritional antioxidants sulforaphane and hydroxytyrosol against particular signs and symptoms of AD. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Manuela Pennisi
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy.,Spinal Unit, Emergency Hospital "Cannizzaro,", Catania, Italy
| | - Rosalia Crupi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Rosanna Di Paola
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Maria Laura Ontario
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
| | - Rita Bella
- Department of Medical and Surgical Sciences and Advanced Technologies, Section of Neurosciences, University of Catania, Catania, Italy
| | - Edward J Calabrese
- Environmental Health Sciences Division, School of Public Health, University of Massachusetts, Amherst, Massachusetts
| | | | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Vittorio Calabrese
- Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, Catania, Italy
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17
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Kim JY, Paton JC, Briles DE, Rhee DK, Pyo S. Streptococcus pneumoniae induces pyroptosis through the regulation of autophagy in murine microglia. Oncotarget 2016; 6:44161-78. [PMID: 26683708 PMCID: PMC4792549 DOI: 10.18632/oncotarget.6592] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/26/2015] [Indexed: 01/14/2023] Open
Abstract
Streptococcus pneumoniae is responsible for significant mortality and morbidity worldwide and causes invasive pneumococcal diseases including pneumococcal meningitis. Pyroptosis is caspase-1-dependent inflammatory cell death and is known to be induced by various microbial infections. In the present study, we investigated the molecular mechanisms that regulate pyroptosis induced by S. pneumoniae in microglia. Our results revealed that S. pneumoniae induced pyroptosis through caspase-1 activation and IL-1β production. We also found that the activation of caspase-1 and the maturation of IL-1β and IL-18 in the S. pneumoniae-triggered pyroptotic cell death process were mediated by NLRP3 inflammasome. In addition, pneumococcal infection increased the expression of autophagy-related genes and induced autophagosome formation. We also showed that the inhibition of autophagy promoted pneumococcus-induced pyroptosis. Furthermore, ROS was generated by pneumococcal infection and inhibited caspase-1 activation within 4 h of infection. However, in the late phase of infection, IL-1β secretion and caspase-1-dependent cell death were induced by ROS. These results suggest that autophagy induction transiently delay pyroptosis induced by S. pneumoniae in microglia. Our study also revealed that the activation of caspase-1 and the production of IL-1β were induced by pneumolysin and that pneumolysin triggered pyroptosis in microglial cells. Similar to the in vitro results, S. pneumoniae induced caspase-1 activation and caspase-1-dependent cytokine maturation in the mouse meningitis model. Thus, the present data demonstrate that S. pneumoniae induces pyroptosis in murine microglia and that NLRP3 inflammasome is critical for caspase-1 activation during the process. Furthermore, the induction of autophagy could transiently protect microglia from pyroptosis.
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Affiliation(s)
- Ji-Yun Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-do, Republic of Korea
| | - James C Paton
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
| | - David E Briles
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Genetics, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Dong-Kwon Rhee
- School of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-do, Republic of Korea
| | - Suhkneung Pyo
- School of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-do, Republic of Korea
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18
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Kim J, Park J, Eisenhut M, Yu J, Shin J. Inflammasome activation by cell volume regulation and inflammation-associated hyponatremia: A vicious cycle. Med Hypotheses 2016; 93:117-21. [DOI: 10.1016/j.mehy.2016.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/17/2016] [Accepted: 05/18/2016] [Indexed: 12/16/2022]
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19
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Shi F, Kouadir M, Yang Y. NALP3 inflammasome activation in protein misfolding diseases. Life Sci 2015; 135:9-14. [DOI: 10.1016/j.lfs.2015.05.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 04/09/2015] [Accepted: 05/03/2015] [Indexed: 01/26/2023]
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20
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Nuvolone M, Sorce S, Schwarz P, Aguzzi A. Prion pathogenesis in the absence of NLRP3/ASC inflammasomes. PLoS One 2015; 10:e0117208. [PMID: 25671600 PMCID: PMC4324825 DOI: 10.1371/journal.pone.0117208] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/19/2014] [Indexed: 12/31/2022] Open
Abstract
The accumulation of the scrapie prion protein PrPSc, a misfolded conformer of the cellular prion protein PrPC, is a crucial feature of prion diseases. In the central nervous system, this process is accompanied by conspicuous microglia activation. The NLRP3 inflammasome is a multi-molecular complex which can sense heterogeneous pathogen-associated molecular patterns and culminates in the activation of caspase 1 and release of IL 1β. The NLRP3 inflammasome was reported to be essential for IL 1β release after in vitro exposure to the amyloidogenic peptide PrP106-126 and to recombinant PrP fibrils. We therefore studied the role of the NLRP3 inflammasome in a mouse model of prion infection. Upon intracerebral inoculation with scrapie prions (strain RML), mice lacking NLRP3 (Nlrp3-/-) or the inflammasome adaptor protein ASC (Pycard-/-) succumbed to scrapie with attack rates and incubation times similar to wild-type mice, and developed the classic histologic and biochemical features of prion diseases. Genetic ablation of NLRP3 or ASC did not significantly impact on brain levels of IL 1β at the terminal stage of disease. Our results exclude a significant role for NLRP3 and ASC in prion pathogenesis and invalidate their claimed potential as therapeutic target against prion diseases.
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Affiliation(s)
- Mario Nuvolone
- Institute of Neuropathology, University Hospital of Zurich, Zurich, Switzerland
- * E-mail: (AA); (MN)
| | - Silvia Sorce
- Institute of Neuropathology, University Hospital of Zurich, Zurich, Switzerland
| | - Petra Schwarz
- Institute of Neuropathology, University Hospital of Zurich, Zurich, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University Hospital of Zurich, Zurich, Switzerland
- * E-mail: (AA); (MN)
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21
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Cocco M, Garella D, Di Stilo A, Borretto E, Stevanato L, Giorgis M, Marini E, Fantozzi R, Miglio G, Bertinaria M. Electrophilic warhead-based design of compounds preventing NLRP3 inflammasome-dependent pyroptosis. J Med Chem 2014; 57:10366-82. [PMID: 25418070 DOI: 10.1021/jm501072b] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pyroptosis is a caspase-1-dependent pro-inflammatory form of programmed cell death implicated in the pathogenesis of autoinflammatory diseases as well as in disorders characterized by excessive cell death and inflammation. Activation of NLRP3 inflammasome is a key event in the pyroptotic cascade. In this study, we describe the synthesis and chemical tuning of α,β-unsaturated electrophilic warheads toward the development of antipyroptotic compounds. Their pharmacological evaluation and structure-activity relationships are also described. Compound 9 was selected as a model of this series, and it proved to be a reactive Michael acceptor, irreversibly trapping thiol nucleophiles, which prevented both ATP- and nigericin-triggered pyroptosis of human THP-1 cells in a time- and concentration-dependent manner. Moreover, 9 and other structurally related compounds, inhibited caspase-1 and NLRP3 ATPase activities. Our findings can contribute to the development of covalent, multitarget antipyroptotic compounds targeting molecular components of the NLRP3 inflammasome regulatory pathway.
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Affiliation(s)
- Mattia Cocco
- Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino , Via P. Giuria 9, 10125 Torino, Italy
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22
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Kigerl KA, de Rivero Vaccari JP, Dietrich WD, Popovich PG, Keane RW. Pattern recognition receptors and central nervous system repair. Exp Neurol 2014; 258:5-16. [PMID: 25017883 DOI: 10.1016/j.expneurol.2014.01.001] [Citation(s) in RCA: 322] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 12/31/2013] [Accepted: 01/02/2014] [Indexed: 12/12/2022]
Abstract
Pattern recognition receptors (PRRs) are part of the innate immune response and were originally discovered for their role in recognizing pathogens by ligating specific pathogen associated molecular patterns (PAMPs) expressed by microbes. Now the role of PRRs in sterile inflammation is also appreciated, responding to endogenous stimuli referred to as "damage associated molecular patterns" (DAMPs) instead of PAMPs. The main families of PRRs include Toll-like receptors (TLRs), Nod-like receptors (NLRs), RIG-like receptors (RLRs), AIM2-like receptors (ALRs), and C-type lectin receptors. Broad expression of these PRRs in the CNS and the release of DAMPs in and around sites of injury suggest an important role for these receptor families in mediating post-injury inflammation. Considerable data now show that PRRs are among the first responders to CNS injury and activation of these receptors on microglia, neurons, and astrocytes triggers an innate immune response in the brain and spinal cord. Here we discuss how the various PRR families are activated and can influence injury and repair processes following CNS injury.
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Affiliation(s)
- Kristina A Kigerl
- Department of Neuroscience - Center for Brain and Spinal Cord Repair, Wexner Medical Center at The Ohio State University, USA
| | | | - W Dalton Dietrich
- Department of Neurological Surgery - The Miami Project to Cure Paralysis, USA
| | - Phillip G Popovich
- Department of Neuroscience - Center for Brain and Spinal Cord Repair, Wexner Medical Center at The Ohio State University, USA.
| | - Robert W Keane
- Department of Physiology & Biophysics - University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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23
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Liu Y, Zhang R, Yan K, Chen F, Huang W, Lv B, Sun C, Xu L, Li F, Jiang X. Mesenchymal stem cells inhibit lipopolysaccharide-induced inflammatory responses of BV2 microglial cells through TSG-6. J Neuroinflammation 2014; 11:135. [PMID: 25088370 PMCID: PMC4128538 DOI: 10.1186/1742-2094-11-135] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 07/21/2014] [Indexed: 12/20/2022] Open
Abstract
Microglia are the primary immunocompetent cells in brain tissue and microglia-mediated inflammation is associated with the pathogenesis of various neuronal disorders. Recently, many studies have shown that mesenchymal stem cells (MSCs) display a remarkable ability to modulate inflammatory and immune responses through the release of a variety of bioactive molecules, thereby protecting the central nervous system. Previously, we reported that MSCs have the ability to modulate inflammatory responses in a traumatic brain injury model and that the potential mechanisms may be partially attributed to upregulated TNF-α stimulated gene/protein 6 (TSG-6) expression. However, whether TSG-6 exerts an anti-inflammatory effect by affecting microglia is not fully understood. In this study, we investigated the anti-inflammatory effects of MSCs and TSG-6 in an in vitro lipopolysaccharide (LPS)-induced BV2 microglial activation model. We found that MSCs and TSG-6 significantly inhibited the expression of pro-inflammatory mediators in activated microglia. However, MSC effects on microglia were attenuated when TSG-6 expression was silenced. In addition, we found that the activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) pathways in LPS-stimulated BV2 microglial cells was significantly inhibited by TSG-6. Furthermore, we found that the presence of CD44 in BV2 microglial cells was essential for MSC- and TSG-6-mediated inhibition of pro-inflammatory gene expression and of NF-κB and MAPK activation in BV2 microglial cells. The results of this study suggest that MSCs can modulate microglia activation through TSG-6 and that TSG-6 attenuates the inflammatory cascade in activated microglia. Our study indicates that novel mechanisms are responsible for the immunomodulatory effect of MSCs on microglia and that MSCs, as well as TSG-6, might be promising therapeutic agents for the treatment of neurotraumatic injuries or neuroinflammatory diseases associated with microglial activation.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Xiaodan Jiang
- The National Key Clinic Specialty, the Neurosurgery Institute of Guangdong Province, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, 253# Gongye Road, Guangzhou 510282, China.
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Song ZQ, Yang LF, Wang YS, Zhu T, Zhou XM, Yin XM, Yao HQ, Zhao DM. Overexpression of BAT3 alleviates prion protein fragment PrP106-126-induced neuronal apoptosis. CNS Neurosci Ther 2014; 20:737-47. [PMID: 24629137 PMCID: PMC6493199 DOI: 10.1111/cns.12243] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/03/2014] [Accepted: 02/03/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUNDS AND AIMS Prion diseases are a group of infectious neurodegenerative diseases characterized by neuronal death and degeneration. Human leukocyte antigen-B-associated transcript 3 (BAT3) is an important apoptosis regulator. We therefore investigated the interactions between BAT3 and prion protein and the potential role of BAT3 in PrP106-126-induced apoptosis. METHODS BAT3 and prion protein were overexpressed in Hela, Neuro2A, or primary neuronal cells by transfection with BAT3-HA or PRNP-EGFP expression plasmids and their relationship studied by immunofluorescence and Western blotting. The effect of BAT3 on PrP106-126-induced cytotoxicity and apoptosis was detected by the CCK-8 assay and terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. The expression of cytochrome c and Bcl-2 was examined by Western blotting. RESULTS BAT3 interacted with prion protein and enhanced PrP expression. After PrP106-126 peptide treated, BAT3 was transported from the nucleus to cytoplasm, increased cell viability, and protected neurons from PrP106-126-induced apoptosis through stabilizing the level of Bcl-2 protein and inhibiting the release of cytochrome c to cytoplasm. CONCLUSIONS Our present data showed a novel molecular mechanism of PrP106-126-induced apoptotic process regulation through the overexpression of BAT3, which may be important for the basic regulatory mechanism of neuron survival in prion diseases and associated neurodegenerative diseases in vivo.
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Affiliation(s)
- Zhi-Qi Song
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
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Activation and regulation of cellular inflammasomes: gaps in our knowledge for central nervous system injury. J Cereb Blood Flow Metab 2014; 34:369-75. [PMID: 24398940 PMCID: PMC3948131 DOI: 10.1038/jcbfm.2013.227] [Citation(s) in RCA: 246] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 11/19/2013] [Accepted: 12/01/2013] [Indexed: 02/07/2023]
Abstract
The inflammasome is an intracellular multiprotein complex involved in the activation of caspase-1 and the processing of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18. The inflammasome in the central nervous system (CNS) is involved in the generation of an innate immune inflammatory response through IL-1 cytokine release and in cell death through the process of pyroptosis. In this review, we consider the different types of inflammasomes (NLRP1, NLRP2, NLRP3, and AIM2) that have been described in CNS cells, namely neurons, astrocytes, and microglia. Importantly, we focus on the role of the inflammasome after brain and spinal cord injury and cover the potential activators of the inflammasome after CNS injury such as adenosine triphosphate and DNA, and the therapeutic potential of targeting the inflammasome to improve outcomes after CNS trauma.
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Fann DYW, Lee SY, Manzanero S, Chunduri P, Sobey CG, Arumugam TV. Pathogenesis of acute stroke and the role of inflammasomes. Ageing Res Rev 2013; 12:941-66. [PMID: 24103368 DOI: 10.1016/j.arr.2013.09.004] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 09/12/2013] [Accepted: 09/19/2013] [Indexed: 12/20/2022]
Abstract
Inflammation is an innate immune response to infection or tissue damage that is designed to limit harm to the host, but contributes significantly to ischemic brain injury following stroke. The inflammatory response is initiated by the detection of acute damage via extracellular and intracellular pattern recognition receptors, which respond to conserved microbial structures, termed pathogen-associated molecular patterns or host-derived danger signals termed damage-associated molecular patterns. Multi-protein complexes known as inflammasomes (e.g. containing NLRP1, NLRP2, NLRP3, NLRP6, NLRP7, NLRP12, NLRC4, AIM2 and/or Pyrin), then process these signals to trigger an effector response. Briefly, signaling through NLRP1 and NLRP3 inflammasomes produces cleaved caspase-1, which cleaves both pro-IL-1β and pro-IL-18 into their biologically active mature pro-inflammatory cytokines that are released into the extracellular environment. This review will describe the molecular structure, cellular signaling pathways and current evidence for inflammasome activation following cerebral ischemia, and the potential for future treatments for stroke that may involve targeting inflammasome formation or its products in the ischemic brain.
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