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Thakku Sivakumar D, Jain K, Alfehaid N, Wang Y, Teng X, Fischer W, Engel T. The Purinergic P2X7 Receptor as a Target for Adjunctive Treatment for Drug-Refractory Epilepsy. Int J Mol Sci 2024; 25:6894. [PMID: 39000004 PMCID: PMC11241490 DOI: 10.3390/ijms25136894] [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: 04/17/2024] [Revised: 06/06/2024] [Accepted: 06/17/2024] [Indexed: 07/14/2024] Open
Abstract
Epilepsy is one of the most common neurological diseases worldwide. Anti-seizure medications (ASMs) with anticonvulsants remain the mainstay of epilepsy treatment. Currently used ASMs are, however, ineffective to suppress seizures in about one third of all patients. Moreover, ASMs show no significant impact on the pathogenic mechanisms involved in epilepsy development or disease progression and may cause serious side-effects, highlighting the need for the identification of new drug targets for a more causal therapy. Compelling evidence has demonstrated a role for purinergic signalling, including the nucleotide adenosine 5'-triphosphate (ATP) during the generation of seizures and epilepsy. Consequently, drugs targeting specific ATP-gated purinergic receptors have been suggested as promising treatment options for epilepsy including the cationic P2X7 receptor (P27XR). P2X7R protein levels have been shown to be increased in the brain of experimental models of epilepsy and in the resected brain tissue of patients with epilepsy. Animal studies have provided evidence that P2X7R blocking can reduce the severity of acute seizures and the epileptic phenotype. The current review will provide a brief summary of recent key findings on P2X7R signalling during seizures and epilepsy focusing on the potential clinical use of treatments based on the P2X7R as an adjunctive therapeutic strategy for drug-refractory seizures and epilepsy.
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Affiliation(s)
- Divyeshz Thakku Sivakumar
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, D02 YN77 Dublin, Ireland
| | - Krishi Jain
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, D02 YN77 Dublin, Ireland
| | - Noura Alfehaid
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, D02 YN77 Dublin, Ireland
| | - Yitao Wang
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, D02 YN77 Dublin, Ireland
- International College of Pharmaceutical Innovation, Soochow University, Suzhou 215123, China
| | - Xinchen Teng
- International College of Pharmaceutical Innovation, Soochow University, Suzhou 215123, China
| | | | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, D02 YN77 Dublin, Ireland
- FutureNeuro, Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, D02 YN77 Dublin, Ireland
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Zhou C, Satpute V, Yip KL, Anderson LL, Hawkins N, Kearney J, Arnold JC. A high seizure burden increases several prostaglandin species in the hippocampus of a Scn1a +/- mouse model of Dravet syndrome. Prostaglandins Other Lipid Mediat 2024; 172:106836. [PMID: 38599513 DOI: 10.1016/j.prostaglandins.2024.106836] [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: 01/09/2024] [Revised: 04/02/2024] [Accepted: 04/05/2024] [Indexed: 04/12/2024]
Abstract
Dravet syndrome is an intractable epilepsy with a high seizure burden that is resistant to current anti-seizure medications. There is evidence that neuroinflammation plays a role in epilepsy and seizures, however few studies have specifically examined neuroinflammation in Dravet syndrome under conditions of a higher seizure burden. Here we used an established genetic mouse model of Dravet syndrome (Scn1a+/- mice), to examine whether a higher seizure burden impacts the number and morphology of microglia in the hippocampus. Moreover, we examined whether a high seizure burden influences classical inflammatory mediators in this brain region. Scn1a+/- mice with a high seizure burden induced by thermal priming displayed a localised reduction in microglial cell density in the granule cell layer and subgranular zone of the dentate gyrus, regions important to postnatal neurogenesis. However, microglial cell number and morphology remained unchanged in other hippocampal subfields. The high seizure burden in Scn1a+/- mice did not affect hippocampal mRNA expression of classical inflammatory mediators such as interleukin 1β and tumour necrosis factor α, but increased cyclooxygenase 2 (COX-2) expression. We then quantified hippocampal levels of prostanoids that arise from COX-2 mediated metabolism of fatty acids and found that Scn1a+/- mice with a high seizure burden displayed increased hippocampal concentrations of numerous prostaglandins, notably PGF2α, PGE2, PGD2, and 6-K-PGF1A, compared to Scn1a+/- mice with a low seizure burden. In conclusion, a high seizure burden increased hippocampal concentrations of various prostaglandin mediators in a mouse model of Dravet syndrome. Future studies could interrogate the prostaglandin pathways to further better understand their role in the pathophysiology of Dravet syndrome.
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Affiliation(s)
- Cilla Zhou
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia; Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia; Department of Pharmacology, Feinberg School of Medicine, Northwestern University, IL 60611, USA
| | - Vaishali Satpute
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia; Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
| | - Ka Lai Yip
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia; Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
| | - Lyndsey L Anderson
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia; Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
| | - Nicole Hawkins
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, IL 60611, USA
| | - Jennifer Kearney
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, IL 60611, USA
| | - Jonathon C Arnold
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia; Discipline of Pharmacology, School of Pharmacy, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia.
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Zuo C, Xu YS, He PF, Zhang WJ. ATP ion channel P2X7 receptor as a regulatory molecule in the progression of colorectal cancer. Eur J Med Chem 2023; 261:115877. [PMID: 37857146 DOI: 10.1016/j.ejmech.2023.115877] [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: 08/22/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 10/21/2023]
Abstract
Large amounts of adenosine triphosphate (ATP), a natural P2X7 receptor activator, are released during colorectal carcinogenesis. P2X7 receptor activation regulates the activity of colorectal cancer (CRC) cells by mediating intracellular signal transduction. Importantly, the opening and activation of membrane pores of P2X7 receptor are different, which can play a dual role in promoting or inhibiting the progression of CRC. These can also depend on P2X7 receptor to regulate the activities of immune cells in the microenvironment, play the functions of immune regulation, immune escape and immune monitoring. While the use of P2X7 receptor antagonists (such as BBG, A438079 and A740003) can play a certain inhibitory pharmacological role on the activity of CRC. Therefore, in this paper, the mechanism and immunomodulatory function of P2X7 receptor involved in the progression of CRC were discussed. Moreover, we discussed the effect of antagonizing the activity of P2X7 receptor on the progression of CRC. So P2X7 receptor may be a new pharmacological molecular target for the treatment of CRC.
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Affiliation(s)
- Cheng Zuo
- Gastrointestinal Surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province, 343000, China
| | - Yong-Sheng Xu
- Gastrointestinal Surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province, 343000, China
| | - Peng-Fei He
- Gastrointestinal Surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province, 343000, China
| | - Wen-Jun Zhang
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province, 343000, China.
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The P2X7 Receptor as a Mechanistic Biomarker for Epilepsy. Int J Mol Sci 2023; 24:ijms24065410. [PMID: 36982485 PMCID: PMC10049244 DOI: 10.3390/ijms24065410] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/03/2023] [Accepted: 03/07/2023] [Indexed: 03/14/2023] Open
Abstract
Epilepsy, characterized by recurrent spontaneous seizures, is a heterogeneous group of brain diseases affecting over 70 million people worldwide. Major challenges in the management of epilepsy include its diagnosis and treatment. To date, video electroencephalogram (EEG) monitoring is the gold-standard diagnostic method, with no molecular biomarker in routine clinical use. Moreover, treatment based on anti-seizure medications (ASMs) remains ineffective in 30% of patients, and, even if seizure-suppressive, lacks disease-modifying potential. Current epilepsy research is, therefore, mainly focussed on the identification of new drugs with a different mechanism of action effective in patients not responding to current ASMs. The vast heterogeneity of epilepsy syndromes, including differences in underlying pathology, comorbidities and disease progression, represents, however, a particular challenge in drug discovery. Optimal treatment most likely requires the identification of new drug targets combined with diagnostic methods to identify patients in need of a specific treatment. Purinergic signalling via extracellularly released ATP is increasingly recognized to contribute to brain hyperexcitability and, consequently, drugs targeting this signalling system have been proposed as a new therapeutic strategy for epilepsy. Among the purinergic ATP receptors, the P2X7 receptor (P2X7R) has attracted particular attention as a novel target for epilepsy treatment, with P2X7Rs contributing to unresponsiveness to ASMs and drugs targeting the P2X7R modulating acute seizure severity and suppressing seizures during epilepsy. In addition, P2X7R expression has been reported to be altered in the brain and circulation in experimental models of epilepsy and patients, making it both a potential therapeutic and diagnostic target. The present review provides an update on the newest findings regarding P2X7R-based treatments for epilepsy and discusses the potential of P2X7R as a mechanistic biomarker.
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Wong ZW, Engel T. More than a drug target: Purinergic signalling as a source for diagnostic tools in epilepsy. Neuropharmacology 2023; 222:109303. [PMID: 36309046 DOI: 10.1016/j.neuropharm.2022.109303] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/15/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
Epilepsy is one of the most common and disabling chronic neurological diseases affecting people of all ages. Major challenges of epilepsy management include the persistently high percentage of drug-refractoriness among patients, the absence of disease-modifying treatments, and its diagnosis and prognosis. To date, long-term video-electroencephalogram (EEG) recordings remain the gold standard for an epilepsy diagnosis. However, this is very costly, has low throughput, and in some instances has very limited availability. Therefore, much effort is put into the search for non-invasive diagnostic tests. Purinergic signalling, via extracellularly released adenosine triphosphate (ATP), is gaining increasing traction as a therapeutic strategy for epilepsy treatment which is supported by evidence from both experimental models and patients. This includes in particular the ionotropic P2X7 receptor. Besides that, other components from the ATPergic signalling cascade such as the metabotropic P2Y receptors (e.g., P2Y1 receptor) and ATP-release channels (e.g., pannexin-1), have also been shown to contribute to seizures and epilepsy. In addition to the therapeutic potential of purinergic signalling, emerging evidence has also shown its potential as a diagnostic tool. Following seizures and epilepsy, the concentration of purines in the blood and the expression of different compounds of the purinergic signalling cascade are significantly altered. Herein, this review will provide a detailed discussion of recent findings on the diagnostic potential of purinergic signalling for epilepsy management and the prospect of translating it for clinical application. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.
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Affiliation(s)
- Zheng Wei Wong
- School of Pharmacy, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia
| | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin, D02 YN77, Ireland; FutureNeuro, Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin, D02 YN77, Ireland.
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Gómez-Pinedo U, Torre-Fuentes L, Matías-Guiu JA, Pytel V, Ojeda-Hernández DD, Selma-Calvo B, Montero-Escribano P, Vidorreta-Ballesteros L, Matías-Guiu J. Exonic variants of the P2RX7 gene in familial multiple sclerosis. Neurologia 2022:S2173-5808(22)00189-4. [PMID: 36470550 DOI: 10.1016/j.nrleng.2022.12.001] [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: 09/09/2022] [Accepted: 10/09/2022] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Several studies have analysed the presence of P2RX7 variants in patients with MS, reporting diverging results. METHODS Our study analyses P2RX7 variants detected through whole-exome sequencing (WES). RESULTS We analysed P2RX7, P2RX4, and CAMKK2 gene variants detected by whole-exome sequencing in all living members (n = 127) of 21 families including at least 2 individuals with multiple sclerosis. P2RX7 gene polymorphisms previously associated with autoimmune disease. Although no differences were observed between individuals with and without multiple sclerosis, we found greater polymorphism of gain-of-function variants of P2RX7 in families with individuals with multiple sclerosis than in the general population. Copresence of gain-of-function and loss-of-function variants was not observed to reduce the risk of presenting the disease. Three families displayed heterozygous gain-of-function SNPs in patients with multiple sclerosis but not in healthy individuals. We were unable to determine the impact of copresence of P2RX4 and CAMKK2 variants with P2RX7 variants, or the potential effect of the different haplotypes described in the gene. No clinical correlations with other autoimmune diseases were observed in our cohort. CONCLUSIONS Our results support the hypothesis that the disease is polygenic and point to a previously unknown mechanism of genetic predisposition to familial forms of multiple sclerosis. P2RX7 gene activity can be modified, which suggests the possibility of preventive pharmacological treatments for families including patients with familial multiple sclerosis.
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Affiliation(s)
- U Gómez-Pinedo
- Laboratory of Neurobiology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain.
| | - L Torre-Fuentes
- Laboratory of Neurobiology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - J A Matías-Guiu
- Department of Neurology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - V Pytel
- Laboratory of Neurobiology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain; Department of Neurology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - D D Ojeda-Hernández
- Laboratory of Neurobiology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - B Selma-Calvo
- Laboratory of Neurobiology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - P Montero-Escribano
- Department of Neurology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - L Vidorreta-Ballesteros
- Department of Neurology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
| | - J Matías-Guiu
- Laboratory of Neurobiology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain; Department of Neurology, Institute of Neurosciences, IdISSC, Hospital Clínico San Carlos, Universidad Complutense de Madrid, Madrid, Spain
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Hua SQ, Hu JL, Zou FL, Liu JP, Luo HL, Hu DX, Wu LD, Zhang WJ. P2X7 receptor in inflammation and pain. Brain Res Bull 2022; 187:199-209. [PMID: 35850190 DOI: 10.1016/j.brainresbull.2022.07.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/15/2022] [Accepted: 07/13/2022] [Indexed: 11/02/2022]
Abstract
Different studies have confirmed P2X7 receptor-mediated inflammatory mediators play a key role in the development of pain. P2X7 receptor activation can induce the development of pain by mediating the release of inflammatory mediators. In view of the fact that P2X7 receptor is expressed in the nervous system and immune system, it is closely related to the stability and maintenance of the nervous system function. ATP activates P2X7 receptor, opens non-selective cation channels, activates multiple intracellular signaling, releases multiple inflammatory cytokines, and induces pain. At present, the role of P2X7 receptor in inflammatory response and pain has been widely recognized and affirmed. Therefore, in this paper, we discussed the pathological mechanism of P2X7 receptor-mediated inflammation and pain, focused on the internal relationship between P2X7 receptor and pain. Moreover, we also described the effects of some antagonists on pain relief by inhibiting the activities of P2X7 receptor. Thus, targeting to inhibit activation of P2X7 receptor is expected to become another potential target for the relief of pain.
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Affiliation(s)
- Shi-Qi Hua
- Nanchang University, Nanchang City 343000, Jiangxi Province, China
| | - Jia-Ling Hu
- Emergency Department, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China
| | - Fei-Long Zou
- Gastrointestinal Surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China
| | - Ji-Peng Liu
- Gastrointestinal Surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China
| | - Hong-Liang Luo
- Gastrointestinal Surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China
| | - Dong-Xia Hu
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China.
| | - Li-Dong Wu
- Emergency Department, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China.
| | - Wen-Jun Zhang
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Nanchang University, Nanchang City 343000, Jiangxi Province, China.
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Beyond Seizure Control: Treating Comorbidities in Epilepsy via Targeting of the P2X7 Receptor. Int J Mol Sci 2022; 23:ijms23042380. [PMID: 35216493 PMCID: PMC8875404 DOI: 10.3390/ijms23042380] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/17/2022] Open
Abstract
Epilepsy is one of the most common chronic diseases of the central nervous system (CNS). Treatment of epilepsy remains, however, a clinical challenge with over 30% of patients not responding to current pharmacological interventions. Complicating management of treatment, epilepsy comes with multiple comorbidities, thereby further reducing the quality of life of patients. Increasing evidence suggests purinergic signalling via extracellularly released ATP as shared pathological mechanisms across numerous brain diseases. Once released, ATP activates specific purinergic receptors, including the ionotropic P2X7 receptor (P2X7R). Among brain diseases, the P2X7R has attracted particular attention as a therapeutic target. The P2X7R is an important driver of inflammation, and its activation requires high levels of extracellular ATP to be reached under pathological conditions. Suggesting the therapeutic potential of drugs targeting the P2X7R for epilepsy, P2X7R expression increases following status epilepticus and during epilepsy, and P2X7R antagonism modulates seizure severity and epilepsy development. P2X7R antagonism has, however, also been shown to be effective in treating conditions most commonly associated with epilepsy such as psychiatric disorders and cognitive deficits, which suggests that P2X7R antagonisms may provide benefits beyond seizure control. This review summarizes the evidence suggesting drugs targeting the P2X7R as a novel treatment strategy for epilepsy with a particular focus of its potential impact on epilepsy-associated comorbidities.
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9
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Regulation of P2X7 receptor expression and function in the brain. Brain Res Bull 2018; 151:153-163. [PMID: 30593878 DOI: 10.1016/j.brainresbull.2018.12.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/19/2018] [Accepted: 12/12/2018] [Indexed: 02/07/2023]
Abstract
Because of its prominent role in driving inflammatory processes, the ATP-gated purinergic P2X7 receptor has attracted much attention over the past decade as a potential therapeutic target for numerous human conditions, particularly diseases of the central nervous system, including neurodegenerative diseases (e.g. Alzheimer's and Huntington's disease), psychiatric disorders (e.g. schizophrenia and depression) and the neurological disease, epilepsy. Evidence stems from studies using experimental models and patient tissue showing changes in P2X7 expression and function under pathological conditions and beneficial effects provided by P2X7 antagonism. Apart from promoting neuroinflammation, P2X7, however, also impacts on other pathological processes in the brain, including cell death, hyperexcitability, changes in neurotransmitter release and neurogenesis. Reports also suggest a role for P2X7 in the maintenance of blood-brain-barrier integrity. It therefore comes as no surprise that the regulation of P2X7 expression and function is complex, providing tight control on P2X7 activation. Much progress has been made in understanding how P2X7 is regulated during physiological and pathological conditions and what the consequences are of pathological P2X7 expression and function. Regulatory mechanisms altering P2X7 expression include transcriptional and post-translational regulation including nucleotide polymorphisms, promoter regulation via DNA methylation, transcription factors (e.g. Sp1 and HIF-1α), the generation of different splice variants and receptor phosphorylation, glycosylation and palmitoylation. Finally, more recently, reports have also shown P2X7-targeting by microRNAs, blocking P2X7 translation into functional proteins. The present review provides a broad overview of what is known to-date about the complex regulation of P2X7 expression with a particular emphasis on the brain and how each of these regulatory mechanisms impacts on receptor function and pathology.
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Abstract
PURPOSE OF REVIEW The aim of this study was to assess the seizure manifestations and risk of epilepsy in encephalitis associated with antibodies against neuronal cell-surface (autoimmune encephalitis) or myelin-associated antigens, and to review several chronic epileptic disorders, including Rasmussen's encephalitis, fever-induced refractory epileptic syndromes (FIRES) and new-onset refractory status epilepticus (NORSE). RECENT FINDINGS Seizures are a frequent manifestation of autoimmune encephalitis. Some autoimmune encephalitis may associate with characteristic features: faciobrachial dystonic seizures (anti-LGI1 encephalitis), electroencephalogram extreme delta brush (anti-NMDAR) or multifocal FLAIR-MRI abnormalities (anti-GABAAR). In anti-LGI1 encephalitis, cortical, limbic and basal ganglia dysfunction results in different types of seizures. Autoimmune encephalitis or myelin-antibody associated syndromes are often immunotherapy-responsive and appear to have a low risk for chronic epilepsy. In contrast patients with seizures related to GAD65-antibodies (an intracellular antigen) frequently develop epilepsy and have suboptimal response to treatment (including surgery). Rasmussen's encephalitis or FIRES may occur with autoantibodies of unclear significance and rarely respond to immunotherapy. A study of patients with NORSE showed that 30% developed chronic epilepsy. SUMMARY Although seizures are frequent in all types of autoimmune encephalitis, the risk for chronic epilepsy is dependent on the antigen: lower if located on the cell-surface, and higher if intracellular. For other disorders (Rasmussen's encephalitis, FIRES, NORSE), the prognosis remains poor.
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Hung KL, Liang JS, Wang JS, Chen HJ, Lin LJ, Lu JF. Association of a novel GABRG2 splicing variation and a PTGS2/COX-2 single nucleotide polymorphism with Taiwanese febrile seizures. Epilepsy Res 2017; 129:1-7. [DOI: 10.1016/j.eplepsyres.2016.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/07/2016] [Accepted: 11/12/2016] [Indexed: 01/20/2023]
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Lascano AM, Korff CM, Picard F. Seizures and Epilepsies due to Channelopathies and Neurotransmitter Receptor Dysfunction: A Parallel between Genetic and Immune Aspects. Mol Syndromol 2016; 7:197-209. [PMID: 27781030 DOI: 10.1159/000447707] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Despite intensive research activity leading to many important discoveries, the pathophysiological mechanisms underlying seizures and epilepsy remain poorly understood. An important number of specific gene defects have been related to various forms of epilepsies, and autoimmunity and epilepsy have been associated for a long time. Certain central nervous system proteins have been involved in epilepsy or acute neurological diseases with seizures either due to underlying gene defects or immune dysfunction. Here, we focus on 2 of them that have been the object of particular attention and in-depth research over the past years: the N-methyl-D-aspartate receptor and the leucin-rich glioma-inactivated protein 1 (LGI1). We also describe illustrative examples of situations in which genetics and immunology meet in the complex pathways that underlie seizures and epilepsy.
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Affiliation(s)
- Agustina M Lascano
- EEG and Epilepsy Exploration Unit, University Hospitals Geneva, Geneva, Switzerland
| | - Christian M Korff
- Pediatric Neurology Unit, Child and Adolescent Department, University Hospitals Geneva, Geneva, Switzerland
| | - Fabienne Picard
- EEG and Epilepsy Exploration Unit, University Hospitals Geneva, Geneva, Switzerland
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13
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ATPergic signalling during seizures and epilepsy. Neuropharmacology 2015; 104:140-53. [PMID: 26549853 DOI: 10.1016/j.neuropharm.2015.11.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/01/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022]
Abstract
Much progress has been made over the last few decades in the identification of new anti-epileptic drugs (AEDs). However, 30% of epilepsy patients suffer poor seizure control. This underscores the need to identify alternative druggable neurotransmitter systems and drugs with novel mechanisms of action. An emerging concept is that seizure generation involves a complex interplay between neurons and glial cells at the tripartite synapse and neuroinflammation has been proposed as one of the main drivers of epileptogenesis. The ATP-gated purinergic receptor family is expressed throughout the brain and is functional on neurons and glial cells. ATP is released in high amounts into the extracellular space after increased neuronal activity and during chronic inflammation and cell death to act as a neuro- and gliotransmitter. Emerging work shows pharmacological targeting of ATP-gated purinergic P2 receptors can potently modulate seizure generation, inflammatory processes and seizure-induced brain damage. To date, work showing the functional contribution of P2 receptors has been mainly performed in animal models of acute seizures, in particular, by targeting the ionotropic P2X7 receptor subtype. Other ionotropic P2X and metabotropic P2Y receptor family members have also been implicated in pathological processes following seizures such as the P2X4 receptor and the P2Y12 receptor. However, during epilepsy, the characterization of P2 receptors was mostly restricted to the study of expressional changes of the different receptor subtypes. This review summarizes the work to date on ATP-mediated signalling during seizures and the functional impact of targeting the ATP-gated purinergic receptors on seizures and seizure-induced pathology. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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14
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P2X purinoceptors as a link between hyperexcitability and neuroinflammation in status epilepticus. Epilepsy Behav 2015; 49:8-12. [PMID: 25843343 DOI: 10.1016/j.yebeh.2015.02.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 12/11/2022]
Abstract
There remains a need for more efficacious treatments for status epilepticus. Prolonged seizures result in the release of ATP from cells which activates the P2 class of ionotropic and metabotropic purinoceptors. The P2X receptors gate depolarizing sodium and calcium entry and are expressed by both neurons and glia throughout the brain, and a number of subtypes are upregulated after status epilepticus. Recent studies have explored the in vivo effects of targeting ATP-gated P2X receptors in preclinical models of status epilepticus, with particular focus on the P2X7 receptor (P2X7R). The P2X7R mediates microglial activation and the release of the proepileptogenic inflammatory cytokine interleukin 1β. The receptor may also directly modulate neurotransmission and gliotransmission and promote the recruitment of immune cells into brain parenchyma. Data from our group and collaborators show that status epilepticus produced by intraamygdala microinjection of kainic acid increases P2X7R expression in the hippocampus and neocortex of mice. Antagonism of the P2X7R in the model reduced seizure severity, microglial activation and interleukin 1β release, and neuronal injury. Coadministration of a P2X7R antagonist with a benzodiazepine also provided seizure suppression in a model of drug-refractory status epilepticus when either treatment alone was minimally effective. More recently, we showed that status epilepticus in immature rats is also reduced by P2X7R antagonism. Together, these findings suggest that P2X receptors may be novel targets for seizure control and interruption of neuroinflammation after status epilepticus. This article is part of a Special Issue entitled "Status Epilepticus".
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Zare-Shahabadi A, Ashrafi MR, Shahrokhi A, Soltani S, Zoghi S, Soleimani F, Vameghi R, Badv RS, Rezaei N. Single nucleotide polymorphisms of TNF-Α gene in febrile seizures. J Neurol Sci 2015; 356:153-6. [PMID: 26119396 DOI: 10.1016/j.jns.2015.06.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 06/20/2015] [Accepted: 06/22/2015] [Indexed: 11/17/2022]
Abstract
Febrile seizures (FS) is the most common seizure disorder during childhood. This study was performed in 78 patients with FS and 137 control subjects to assess polymorphisms of the TNF-α gene at positions -308 and -238, using the polymerase chain reaction and the sequence specific primers method. The highest positive allelic association that made the patients susceptible to FS was seen for TNF-α -238/G (p<0.0001). The GG genotype at TNF-α -238 was significantly higher in the patients with FS, compared to the controls (p=0.0001). Also, GA genotype at the same position was significantly lower in patients than in controls (P=0.0001). The GG haplotype had a significant positive association at TNF-α (308, 238) while GA haplotype showed a negative association (P<0.001). Our data support the idea that TNF-α single-nucleotide polymorphisms play a role in the pathogenesis of FS.
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Affiliation(s)
- Ameneh Zare-Shahabadi
- Molecular Immunology Research Center and Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Mahmoud Reza Ashrafi
- Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Amin Shahrokhi
- Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Samaneh Soltani
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Samaneh Zoghi
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Farin Soleimani
- Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Roshanak Vameghi
- Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Reza Shervin Badv
- Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Nima Rezaei
- Molecular Immunology Research Center and Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Universal Scientific Education and Research Network (USERN), Tehran, Iran.
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16
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Non-synonymous single nucleotide polymorphisms in the P2X receptor genes: association with diseases, impact on receptor functions and potential use as diagnosis biomarkers. Int J Mol Sci 2014; 15:13344-71. [PMID: 25079442 PMCID: PMC4159798 DOI: 10.3390/ijms150813344] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/10/2014] [Accepted: 07/14/2014] [Indexed: 12/17/2022] Open
Abstract
P2X receptors are Ca2+-permeable cationic channels in the cell membranes, where they play an important role in mediating a diversity of physiological and pathophysiological functions of extracellular ATP. Mammalian cells express seven P2X receptor genes. Single nucleotide polymorphisms (SNPs) are widespread in the P2RX genes encoding the human P2X receptors, particularly the human P2X7 receptor. This article will provide an overview of the non-synonymous SNPs (NS-SNPs) that have been associated with or implicated in altering the susceptibility to pathologies or disease conditions, and discuss the consequences of the mutations resulting from such NS-SNPs on the receptor functions. Disease-associated NS-SNPs in the P2RX genes have been valuable in understanding the disease etiology and the receptor function, and are promising as biomarkers to be used for the diagnosis and development of stratified therapeutics.
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