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Witkin JM, Pandey KP, Smith JL. Clinical investigations of compounds targeting metabotropic glutamate receptors. Pharmacol Biochem Behav 2022; 219:173446. [PMID: 35987339 DOI: 10.1016/j.pbb.2022.173446] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/22/2022] [Accepted: 08/08/2022] [Indexed: 11/15/2022]
Abstract
Pharmacological modulation of glutamate has long been considered to be of immense therapeutic utility. The metabotropic glutamate receptors (mGluRs) are potential targets for safely altering glutamate-driven excitation. Data support the potential therapeutic use of mGluR modulators in the treatment of anxiety, depression, schizophrenia, and other psychiatric disorders, pain, epilepsy, as well as neurodegenerative and neurodevelopmental disorders. For each of the three mGluR groups, compounds have been constructed that produce either potentiation or functional blockade. PET ligands for mGlu5Rs have been studied in a range of patient populations and several mGlu5R antagonists have been tested for potential efficacy in patients including mavoglurant, diploglurant, basimglurant, GET 73, and ADX10059. Efficacy with mGlu5R antagonists has been reported in trials with patients with gastroesophageal reflux disease; data from patients with Parkinson's disease or Fragile X syndrome have not been as robust as hoped. Fenobam was approved for use as an anxiolytic prior to its recognition as an mGlu5R antagonist. mGlu2/3R agonists (pomaglumated methionil) and mGlu2R agonists (JNJ-40411813, AZD 8529, and LY2979165) have been studied in patients with schizophrenia with promising but mixed results. Antagonists of mGlu2/3Rs (decoglurant and TS-161) have been studied in depression where TS-161 has advanced into a planned Phase 2 study in treatment-resistant depression. The Group III mGluRs are the least developed of the mGluR receptor targets. The mGlu4R potentiator, foliglurax, did not meet its primary endpoint in patients with Parkinson's disease. Ongoing efforts to develop mGluR-targeted compounds continue to promise these glutamate modulators as medicines for psychiatric and neurological disorders.
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Affiliation(s)
- Jeffrey M Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN, USA; Department of Chemistry & Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA.
| | - Kamal P Pandey
- Department of Chemistry & Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN, USA
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Rettura F, Bronzini F, Campigotto M, Lambiase C, Pancetti A, Berti G, Marchi S, de Bortoli N, Zerbib F, Savarino E, Bellini M. Refractory Gastroesophageal Reflux Disease: A Management Update. Front Med (Lausanne) 2021; 8:765061. [PMID: 34790683 PMCID: PMC8591082 DOI: 10.3389/fmed.2021.765061] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/04/2021] [Indexed: 12/12/2022] Open
Abstract
Gastroesophageal reflux disease (GERD) is one of the most frequent gastrointestinal disorders. Proton pump inhibitors (PPIs) are effective in healing lesions and improving symptoms in most cases, although up to 40% of GERD patients do not respond adequately to PPI therapy. Refractory GERD (rGERD) is one of the most challenging problems, given its impact on the quality of life and consumption of health care resources. The definition of rGERD is a controversial topic as it has not been unequivocally established. Indeed, some patients unresponsive to PPIs who experience symptoms potentially related to GERD may not have GERD; in this case the definition could be replaced with “reflux-like PPI-refractory symptoms.” Patients with persistent reflux-like symptoms should undergo a diagnostic workup aimed at finding objective evidence of GERD through endoscopic and pH-impedance investigations. The management strategies regarding rGERD, apart from a careful check of patient's compliance with PPIs, a possible change in the timing of their administration and the choice of a PPI with a different metabolic pathway, include other pharmacologic treatments. These include histamine-2 receptor antagonists (H2RAs), alginates, antacids and mucosal protective agents, potassium competitive acid blockers (PCABs), prokinetics, gamma aminobutyric acid-B (GABA-B) receptor agonists and metabotropic glutamate receptor-5 (mGluR5) antagonists, and pain modulators. If there is no benefit from medical therapy, but there is objective evidence of GERD, invasive antireflux options should be evaluated after having carefully explained the risks and benefits to the patient. The most widely performed invasive antireflux option remains laparoscopic antireflux surgery (LARS), even if other, less invasive, interventions have been suggested in the last few decades, including endoscopic transoral incisionless fundoplication (TIF), magnetic sphincter augmentation (LINX) or radiofrequency therapy (Stretta). Due to the different mechanisms underlying rGERD, the most effective strategy can vary, and it should be tailored to each patient. The aim of this paper is to review the different management options available to successfully deal with rGERD.
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Affiliation(s)
- Francesco Rettura
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Francesco Bronzini
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Michele Campigotto
- Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Christian Lambiase
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Andrea Pancetti
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Ginevra Berti
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Santino Marchi
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Nicola de Bortoli
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Frank Zerbib
- CHU de Bordeaux, Centre Medico-Chirurgical Magellan, Hôpital Haut-Lévêque, Gastroenterology Department, Université de Bordeaux, INSERM CIC 1401, Bordeaux, France
| | - Edoardo Savarino
- Division of Gastroenterology, Department of Surgery, Oncology and Gastroenterology, University of Padua, Padua, Italy
| | - Massimo Bellini
- Division of Gastroenterology, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
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Abstract
Methamphetamine abuse leads to devastating consequences, including addiction, crime, and death. Despite decades of research, no medication has been approved by the U.S. Food and Drug Administration for the treatment of Methamphetamine Use Disorder. Thus, there is a need for new therapeutic approaches. Animal studies demonstrate that methamphetamine exposure dysregulates forebrain function involving the Group-I metabotropic glutamate receptor subtype 5 (mGlu5), which is predominantly localized to postsynaptic sites. Allosteric modulators of mGlu5 offer a unique opportunity to modulate glutamatergic neurotransmission selectively, thereby potentially ameliorating methamphetamine-induced disruptions. Negative allosteric modulators of mGlu5 attenuate the effects of methamphetamine, including rewarding/reinforcing properties of the drug across animal models, and have shown promising effects in clinical trials for Anxiety Disorder and Major Depressive Disorder. Preclinical studies have also sparked great interest in mGlu5 positive allosteric modulators, which exhibit antipsychotic and anxiolytic properties, and facilitate extinction learning when access to methamphetamine is removed, possibly via the amelioration of methamphetamine-induced cognitive deficits. Clinical research is now needed to elucidate the mechanisms underlying the mGlu5 receptor-related effects of methamphetamine and the contributions of these effects to addictive behaviors. The growing array of mGlu5 allosteric modulators provides excellent tools for this purpose and may offer the prospect of developing tailored and effective medications for Methamphetamine Use Disorder.
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Gregory KJ, Goudet C. International Union of Basic and Clinical Pharmacology. CXI. Pharmacology, Signaling, and Physiology of Metabotropic Glutamate Receptors. Pharmacol Rev 2020; 73:521-569. [PMID: 33361406 DOI: 10.1124/pr.119.019133] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors respond to glutamate, the major excitatory neurotransmitter in the mammalian brain, mediating a modulatory role that is critical for higher-order brain functions such as learning and memory. Since the first mGlu receptor was cloned in 1992, eight subtypes have been identified along with many isoforms and splice variants. The mGlu receptors are transmembrane-spanning proteins belonging to the class C G protein-coupled receptor family and represent attractive targets for a multitude of central nervous system disorders. Concerted drug discovery efforts over the past three decades have yielded a wealth of pharmacological tools including subtype-selective agents that competitively block or mimic the actions of glutamate or act allosterically via distinct sites to enhance or inhibit receptor activity. Herein, we review the physiologic and pathophysiological roles for individual mGlu receptor subtypes including the pleiotropic nature of intracellular signal transduction arising from each. We provide a comprehensive analysis of the in vitro and in vivo pharmacological properties of prototypical and commercially available orthosteric agonists and antagonists as well as allosteric modulators, including ligands that have entered clinical trials. Finally, we highlight emerging areas of research that hold promise to facilitate rational design of highly selective mGlu receptor-targeting therapeutics in the future. SIGNIFICANCE STATEMENT: The metabotropic glutamate receptors are attractive therapeutic targets for a range of psychiatric and neurological disorders. Over the past three decades, intense discovery efforts have yielded diverse pharmacological tools acting either competitively or allosterically, which have enabled dissection of fundamental biological process modulated by metabotropic glutamate receptors and established proof of concept for many therapeutic indications. We review metabotropic glutamate receptor molecular pharmacology and highlight emerging areas that are offering new avenues to selectively modulate neurotransmission.
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Affiliation(s)
- Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
| | - Cyril Goudet
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (K.J.G.) and Institut de Génomique Fonctionnelle (IGF), University of Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Sante et de la Recherche Medicale (INSERM), Montpellier, France (C.G.)
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Jin EH, Park B, Kim YS, Choe EK, Choi SH, Kim JS, Jung SA. A Novel Susceptibility Locus Near GRIK2 Associated With Erosive Esophagitis in a Korean Cohort. Clin Transl Gastroenterol 2020; 11:e00145. [PMID: 32132452 PMCID: PMC7145042 DOI: 10.14309/ctg.0000000000000145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 01/27/2020] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION The male-predominant sex difference through the spectrum of erosive esophagitis to Barrett's esophagus is widely known. We conducted a genome-wide association study (GWAS) stratified by sex for identifying factors that can predict the endoscopically diagnosed erosive esophagitis. METHODS Erosive esophagitis was diagnosed by endoscopy and assessed for severity. We identified genetic factors associated with erosive esophagitis that accounted for the sex differences in a cohort of 4,242 participants via a GWAS. After quality control and imputation, genetic associations with erosive esophagitis were investigated by multivariate linear regression in 3,620 subjects. Single-nucleotide polymorphisms (SNPs) with P < 5.0 × 10 were considered significant genome wide, and a genetic risk score was constructed for the prediction of erosive esophagitis risk. RESULTS Six genome-wide significant SNPs near the GRIK2 gene on chromosome 6 were found to be associated with erosive esophagitis only in male subjects. These were predictive of severity through a genetic risk score (P < 0.05), and the findings were validated in a cohort of 622 subjects (P < 0.05). DISCUSSION This is the first GWAS of erosive esophagitis, and we identified 6 genome-wide significant SNPs in male subjects. These SNPs could help explain the pathogenesis of erosive esophagitis and contribute to the understanding of sex differences. Further genetic investigation could allow for the prediction of high risk for erosive esophagitis and development of new treatment options.
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Affiliation(s)
- Eun Hyo Jin
- Department of Internal Medicine, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
| | - Boram Park
- Department of Public Health Sciences, Seoul National University, Seoul, Korea
| | - Young Sun Kim
- Department of Internal Medicine, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
| | - Eun Kyung Choe
- Department of Surgery, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
| | - Seung Ho Choi
- Department of Internal Medicine, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
| | - Joo Sung Kim
- Department of Internal Medicine, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
- Department of Internal Medicine, Liver Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Sung-Ae Jung
- Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Korea
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Biased agonism and allosteric modulation of metabotropic glutamate receptor 5. Clin Sci (Lond) 2018; 132:2323-2338. [PMID: 30389826 DOI: 10.1042/cs20180374] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 12/18/2022]
Abstract
Metabotropic glutamate receptors belong to class C G-protein-coupled receptors and consist of eight subtypes that are ubiquitously expressed throughout the central nervous system. In recent years, the metabotropic glutamate receptor subtype 5 (mGlu5) has emerged as a promising target for a broad range of psychiatric and neurological disorders. Drug discovery programs targetting mGlu5 are primarily focused on development of allosteric modulators that interact with sites distinct from the endogenous agonist glutamate. Significant efforts have seen mGlu5 allosteric modulators progress into clinical trials; however, recent failures due to lack of efficacy or adverse effects indicate a need for a better understanding of the functional consequences of mGlu5 allosteric modulation. Biased agonism is an interrelated phenomenon to allosterism, describing how different ligands acting through the same receptor can differentially influence signaling to distinct transducers and pathways. Emerging evidence demonstrates that allosteric modulators can induce biased pharmacology at the level of intrinsic agonism as well as through differential modulation of orthosteric agonist-signaling pathways. Here, we present key considerations in the discovery and development of mGlu5 allosteric modulators and the opportunities and pitfalls offered by biased agonism and modulation.
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Roman S, Mion F. Refractory GERD, beyond proton pump inhibitors. Curr Opin Pharmacol 2018; 43:99-103. [PMID: 30240968 DOI: 10.1016/j.coph.2018.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/27/2018] [Accepted: 09/03/2018] [Indexed: 12/22/2022]
Abstract
Pharmacologic therapy, surgery, minimally invasive therapies, and alternative therapies are different options available for the management of refractory GERD. The choice may depend on the cause of refractoriness. Increased gastric acid suppression therapy might be useful in the rare patients with persistent elevated esophageal acid exposure on proton pump inhibitors (PPI). Potassium-competitive acid blockers (P-CAB) might induce a more important acid inhibition than PPI. Baclofen might act as a reflux inhibitor and demonstrates a significant efficacy in rumination syndrome. The role of topical antacid-alginate in refractory GERD might be limited. Surgery might be a valid option in case of persistent pathological acid esophageal exposure despite PPI. Further evaluation of minimally invasive procedures is necessary. Finally diet, diaphragmatic breathing and transcutaneous electrical acustimulation might be of interest in patients with esophageal hypersensivity or functional symptoms.
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Affiliation(s)
- Sabine Roman
- Université de Lyon, Hospices Civils de Lyon, Digestive Physiology, Hopital E Herriot, F-69437, Lyon, France; Université de Lyon, Lyon I University, Digestive Physiology, F-69008, Lyon, France; Université de Lyon, Inserm U1032, LabTAU, F-69008, Lyon, France.
| | - François Mion
- Université de Lyon, Hospices Civils de Lyon, Digestive Physiology, Hopital E Herriot, F-69437, Lyon, France; Université de Lyon, Lyon I University, Digestive Physiology, F-69008, Lyon, France; Université de Lyon, Inserm U1032, LabTAU, F-69008, Lyon, France
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