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Rech L, Dietrich-Ntoukas T, Reinach PS, Brockmann T, Pleyer U, Mergler S. Complement Component C5a and Fungal Pathogen Induce Diverse Responses through Crosstalk between Transient Receptor Potential Channel (TRPs) Subtypes in Human Conjunctival Epithelial Cells. Cells 2024; 13:1329. [PMID: 39195219 DOI: 10.3390/cells13161329] [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: 06/28/2024] [Revised: 08/01/2024] [Accepted: 08/02/2024] [Indexed: 08/29/2024] Open
Abstract
The conjunctiva has immune-responsive properties to protect the eye from infections. Its innate immune system reacts against external pathogens, such as fungi. The complement factor C5a is an important contributor to the initial immune response. It is known that activation of transient-receptor-potential-vanilloid 1 (TRPV1) and TRP-melastatin 8 (TRPM8) channels is involved in different immune reactions and inflammation in the human body. The aim of this study was to determine if C5a and mucor racemosus e voluminae cellulae (MR) modulate Ca2+-signaling through changes in TRPs activity in human conjunctival epithelial cells (HCjECs). Furthermore, crosstalk was examined between C5a and MR in mediating calcium regulation. Intracellular Ca2+-concentration ([Ca2+]i) was measured by fluorescence calcium imaging, and whole-cell currents were recorded using the planar-patch-clamp technique. MR was used as a purified extract. Application of C5a (0.05-50 ng/mL) increased both [Ca2+]i and whole-cell currents, which were suppressed by either the TRPV1-blocker AMG 9810 or the TRPM8-blocker AMTB (both 20 µM). The N-terminal peptide C5L2p (20-50 ng/mL) blocked rises in [Ca2+]i induced by C5a. Moreover, the MR-induced rise in Ca2+-influx was suppressed by AMG 9810 and AMTB, as well as 0.05 ng/mL C5a. In conclusion, crosstalk between C5a and MR controls human conjunctival cell function through modulating interactions between TRPV1 and TRPM8 channel activity.
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Affiliation(s)
- Loreena Rech
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
| | - Tina Dietrich-Ntoukas
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
| | - Peter S Reinach
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325015, China
| | - Tobias Brockmann
- Department of Ophthalmology, Universitätsmedizin Rostock, 18057 Rostock, Germany
- SciTec Department, University of Applied Sciences Jena, 07745 Jena, Germany
| | - Uwe Pleyer
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
| | - Stefan Mergler
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
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2
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Brito LB, Catarino CM, Passos MC, Garcia Silva AC, Schuck DC, Canavez ADPM, Valadares MC. Sens-ocular model: Cell-based assay to evaluate eye stinging potential of chemicals and baby cosmetic formulations. Toxicol In Vitro 2024; 98:105824. [PMID: 38614139 DOI: 10.1016/j.tiv.2024.105824] [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: 11/20/2023] [Revised: 03/01/2024] [Accepted: 04/09/2024] [Indexed: 04/15/2024]
Abstract
The TRPV1 receptor, which is known to contribute significantly to pain perception, has recently been identified as a useful tool for predicting eye stinging potential in cosmetics. In this study, HEK-293 cells with high TRPV1 expression were utilized to evaluate calcium influx related to receptor activation triggered by chemicals and cosmetic formulations. The cells were exposed to increasing concentrations of substances to cause or not some aggression to the eye, and TRPV1 activity was assessed by measuring intracellular FURA-2 AM fluorescence signal. To confirm TRPV1 channel activation, capsazepine, a capsaicin antagonist, was employed in addition to using capsaicin as a positive control. The study's results indicate that this novel model can identify compounds known to cause some aggression to the eye, such as stinging, considering a cut-off value of 60% of Ca2+ influx exposed to the lowest evaluated concentration (0.00032%). When applied to the cosmetic baby formulation, although the presented model exhibited higher sensitivity by classifying as stinging formulations that had previously undergone clinical testing and were deemed non-stinging, the assay could serve as a valuable in vitro tool for predicting human eye stinging sensation and can be used as a tier 1 in an integrated testing strategy.
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Affiliation(s)
- Lara Barroso Brito
- Laboratório de Ensino e Pesquisa em Toxicologia In Vitro - Tox In, Faculdade de Farmácia, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | | | - Maria Claudia Passos
- Laboratório de Ensino e Pesquisa em Toxicologia In Vitro - Tox In, Faculdade de Farmácia, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | - Artur C Garcia Silva
- Laboratório de Ensino e Pesquisa em Toxicologia In Vitro - Tox In, Faculdade de Farmácia, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | | | | | - Marize Campos Valadares
- Laboratório de Ensino e Pesquisa em Toxicologia In Vitro - Tox In, Faculdade de Farmácia, Universidade Federal de Goiás, Goiânia, GO, Brazil.
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3
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Keller M, Mergler S, Li A, Zahn I, Paulsen F, Garreis F. Thermosensitive TRP Channels Are Functionally Expressed and Influence the Lipogenesis in Human Meibomian Gland Cells. Int J Mol Sci 2024; 25:4043. [PMID: 38612853 PMCID: PMC11012639 DOI: 10.3390/ijms25074043] [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: 03/05/2024] [Revised: 03/28/2024] [Accepted: 03/30/2024] [Indexed: 04/14/2024] Open
Abstract
While the involvement of thermosensitive transient receptor potential channels (TRPs) in dry eye disease (DED) has been known for years, their expression in the meibomian gland (MG) has never been investigated. This study aims to show their expression and involvement in the lipogenesis of the MG, providing a possible new drug target in the treatment of DED. Our RT-PCR, Western blot and immunofluorescence analysis showed the expression of TRPV1, TRPV3, TRPV4 and TRPM8 in the MG at the gene and the protein level. RT-PCR also showed gene expression of TRPV2 but not TRPA1. Calcium imaging and planar patch-clamping performed on an immortalized human meibomian gland epithelial cell line (hMGECs) demonstrated increasing whole-cell currents after the application of capsaicin (TRPV1) or icilin (TRPM8). Decreasing whole-cell currents could be registered after the application of AMG9810 (TRPV1) or AMTB (TRPM8). Oil red O staining on hMGECs showed an increase in lipid expression after TRPV1 activation and a decrease after TRPM8 activation. We conclude that thermo-TRPs are expressed at the gene and the protein level in MGs. Moreover, TRPV1 and TRPM8's functional expression and their contribution to their lipid expression could be demonstrated. Therefore, TRPs are potential drug targets and their clinical relevance in the therapy of meibomian gland dysfunction requires further investigation.
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Affiliation(s)
- Melina Keller
- Department of Functional and Clinical Anatomy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Universitätsstraße 19, 91054 Erlangen, Germany (F.P.)
| | - Stefan Mergler
- Department of Ophthalmology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany; (S.M.); (A.L.)
| | - Aruna Li
- Department of Ophthalmology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 13353 Berlin, Germany; (S.M.); (A.L.)
| | - Ingrid Zahn
- Department of Functional and Clinical Anatomy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Universitätsstraße 19, 91054 Erlangen, Germany (F.P.)
| | - Friedrich Paulsen
- Department of Functional and Clinical Anatomy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Universitätsstraße 19, 91054 Erlangen, Germany (F.P.)
| | - Fabian Garreis
- Department of Functional and Clinical Anatomy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Universitätsstraße 19, 91054 Erlangen, Germany (F.P.)
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4
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Tarvestad-Laise KE, Ceresa BP. Modulating Growth Factor Receptor Signaling to Promote Corneal Epithelial Homeostasis. Cells 2023; 12:2730. [PMID: 38067157 PMCID: PMC10706396 DOI: 10.3390/cells12232730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
The corneal epithelium is the first anatomical barrier between the environment and the cornea; it is critical for proper light refraction onto the retina and prevents pathogens (e.g., bacteria, viruses) from entering the immune-privileged eye. Trauma to the highly innervated corneal epithelium is extremely painful and if not resolved quickly or properly, can lead to infection and ultimately blindness. The healthy eye produces its own growth factors and is continuously bathed in tear fluid that contains these proteins and other nutrients to maintain the rapid turnover and homeostasis of the ocular surface. In this article, we review the roles of growth factors in corneal epithelial homeostasis and regeneration and some of the limitations to their use therapeutically.
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Affiliation(s)
- Kate E. Tarvestad-Laise
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA
| | - Brian P. Ceresa
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA
- Department of Ophthalmology and Vision Sciences, University of Louisville, Louisville, KY 40202, USA
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5
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Stasi K, Alshare Q, Jain M, Wald M, Li Y. Topical Ocular TRPV1 Antagonist SAF312 (Libvatrep) Demonstrates Safety, Low Systemic Exposure, and No Anesthetic Effect in Healthy Participants. Transl Vis Sci Technol 2022; 11:15. [DOI: 10.1167/tvst.11.11.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Kalliopi Stasi
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Qusai Alshare
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Monish Jain
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Michael Wald
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Yifang Li
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
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6
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Kalangara JP, Vanijcharoenkarn K, Chisolm S, Kuruvilla ME. Neuropathic pain and itch: mechanisms in allergic conjunctivitis. Curr Opin Allergy Clin Immunol 2022; 22:298-303. [PMID: 35916592 DOI: 10.1097/aci.0000000000000843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Allergic conjunctivitis is highly prevalent and affects up to one third of the general population. The current understanding of the pathophysiology and therapeutic strategies center around the type 2 inflammatory pathway. However, there is an increasing body of evidence that suggests neurogenic mechanisms also play a role in allergic inflammation, with a substantial proportion of allergic conjunctivitis patients experiencing both ocular itch and pain. RECENT FINDINGS Unmyelinated C fibres on the ocular surface transmit histaminergic itch and can be directly activated by mast cell mediators. The conjunctival mucosa also contains TRPV1+ (histamine-dependent) and TRPA1+ (histamine-independent) neurons that enhance ocular pain and itch in allergic conjunctivitis. Allergen-complexed IgE also binds directly to FcεRI expressed on peripheral neurons. Environmental aeroallergens can also directly stimulate neuronal nociceptors to release inflammatory substances. Allergic inflammation thus stimulates nerve terminals to release vasoactive and inflammatory neuropeptides, leading to a cyclical neuronal dysregulation that augments mast cell activity. These repetitive cycles lead to both peripheral and central sensitization and neuronal plasticity, resulting in decreased itch/pain thresholds and a heightened itch/pain response. SUMMARY Neurogenic mechanisms including peripheral and central sensitization may drive chronic ocular itch and pain secondary to allergic inflammation. Research into these pathways may help to identify therapeutic targets in allergic conjunctivitis patients with refractory symptoms.
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Affiliation(s)
| | | | - Sarah Chisolm
- Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia
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7
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Transient Receptor Potential Channels: Important Players in Ocular Pain and Dry Eye Disease. Pharmaceutics 2022; 14:pharmaceutics14091859. [PMID: 36145607 PMCID: PMC9506338 DOI: 10.3390/pharmaceutics14091859] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/26/2022] [Accepted: 08/26/2022] [Indexed: 11/20/2022] Open
Abstract
Dry eye disease (DED) is a multifactorial disorder in which the eyes respond to minor stimuli with abnormal sensations, such as dryness, blurring, foreign body sensation, discomfort, irritation, and pain. Corneal pain, as one of DED’s main symptoms, has gained recognition due to its increasing prevalence, morbidity, and the resulting social burden. The cornea is the most innervated tissue in the body, and the maintenance of corneal integrity relies on a rich density of nociceptors, such as polymodal nociceptor neurons, cold thermoreceptor neurons, and mechano-nociceptor neurons. Their sensory responses to different stimulating forces are linked to the specific expression of transient receptor potential (TRP) channels. TRP channels are a group of unique ion channels that play important roles as cellular sensors for various stimuli. These channels are nonselective cation channels with variable Ca2+ selectivity. TRP homologs are a superfamily of 28 different members that are subdivided into 7 different subfamilies based on differences in sequence homology. Many of these subtypes are expressed in the eye on both neuronal and non-neuronal cells, where they affect various stress-induced regulatory responses essential for normal vision maintenance. This article reviews the current knowledge about the expression, function, and regulation of TRPs in ocular surface tissues. We also describe their implication in DED and ocular pain. These findings contribute to evidence suggesting that drug-targeting TRP channels may be of therapeutic benefit in the clinical setting of ocular pain.
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8
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Galor A, Hamrah P, Haque S, Attal N, Labetoulle M. Understanding chronic ocular surface pain: An unmet need for targeted drug therapy. Ocul Surf 2022; 26:148-156. [PMID: 35970433 DOI: 10.1016/j.jtos.2022.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/29/2022] [Accepted: 08/09/2022] [Indexed: 10/15/2022]
Abstract
Chronic ocular surface pain (COSP) may be defined as a feeling of pain, perceived as originating from the ocular surface, that persists for >3 months. COSP is a complex multifactorial condition associated with several risk factors that may significantly interfere with an individual's daily activities, resulting in poor quality of life (QoL). COSP is also likely to have a high burden on patients with substantial implications on global healthcare costs. While patients may use varied terminology to describe symptoms of COSP, any ocular surface damage in the ocular sensory apparatus (nociceptive, neuropathic, inflammatory, or combination thereof) resulting in low tear production, chronic inflammation, or nerve abnormalities (functional and/or morphological), is typically associated with COSP. Considering the heterogeneity of this condition, it is highly recommended that advanced multimodal diagnostic tools are utilized to help discern the nociceptive and neuropathic pain pathways in order to provide targeted treatment and effective clinical management. The current article provides an overview of COSP, including its multifactorial pathophysiology, etiology, prevalence, clinical presentation, impact on QoL, diagnosis, current management, and unmet medical needs.
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Affiliation(s)
- Anat Galor
- Surgical Services, Miami Veterans Affairs Medical Centre and Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Pedram Hamrah
- Tufts Medical Centre, New England Eye Center, 260 Tremont Street Biewend Building, Boston, MA, USA
| | | | - Nadine Attal
- CHU Paris IdF Ouest - Hôpital Ambroise Paré, 9 avenue Charles de Gaulle, 92100, Boulogne-Billancourt, INSERM U 987 and Université Paris Saclay, France
| | - Marc Labetoulle
- Service d'Ophtalmologie, hôpital Bicêtre, AP-HP, Université Paris Saclay, 94275, Le Kremlin-Bicêtre, France; IMVA-HB/IDMI, CEA, Inserm U1184, 92265, Fontenay-aux-Roses, France.
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9
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Therapeutic Targets in Allergic Conjunctivitis. Pharmaceuticals (Basel) 2022; 15:ph15050547. [PMID: 35631374 PMCID: PMC9147625 DOI: 10.3390/ph15050547] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/18/2022] [Accepted: 04/22/2022] [Indexed: 02/02/2023] Open
Abstract
Allergic conjunctivitis (AC) is a common condition resulting from exposure to allergens such as pollen, animal dander, or mold. It is typically mediated by allergen-induced crosslinking of immunoglobulin E attached to receptors on primed conjunctival mast cells, which results in mast cell degranulation and histamine release, as well as the release of lipid mediators, cytokines, and chemokines. The clinical result is conjunctival hyperemia, tearing, intense itching, and chemosis. Refractory and chronic cases can result in ocular surface complications that may be vision threatening. Patients who experience even mild forms of this disease report an impact on their quality of life. Current treatment options range from non-pharmacologic therapies to ocular and systemic options. However, to adequately control AC, the use of multiple agents is often required. As such, a precise understanding of the immune mechanisms responsible for this ocular surface inflammation is needed to support ongoing research for potential therapeutic targets such as chemokine receptors, cytokine receptors, non-receptor tyrosine kinases, and integrins. This review utilized several published articles regarding the current therapeutic options to treat AC, as well as the pathological and immune mechanisms relevant to AC. This review will also focus on cellular and molecular targets in AC, with particular emphasis on potential therapeutic agents that can attenuate the pathology and immune mechanisms driven by cells, receptors, and molecules that participate in the immunopathogenesis and immunopathology of AC.
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10
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Thébault S. Minireview: Insights into the role of TRP channels in the retinal circulation and function. Neurosci Lett 2021; 765:136285. [PMID: 34634394 DOI: 10.1016/j.neulet.2021.136285] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 08/25/2021] [Accepted: 08/28/2021] [Indexed: 12/17/2022]
Abstract
Consistent with their wide distribution throughout the CNS, transcripts of all transient receptor potential (TRP) cation channel superfamily members have been detected in both neuronal and non-neuronal cells of the mammalian retina. Evidence shows that members of the TRPC (canonical, TRPC1/4/5/6), TRPV (vanilloid, TRPV1/2/4), TRPM (melastatin, TRPM1/2/3/5), TRPA (ankyrin, TRPA1), and TRPP (polycystin, TRPP2) subfamilies contribute to retinal function and circulation in health and disease, but the relevance of most TRPs has yet to be determined. Their principal role in light detection is far better understood than their participation in the control of intraocular pressure, retinal blood flow, oxidative stress, ion homeostasis, and transmitter signaling for retinal information processing. Moreover, if the therapeutic potential of targeting some TRPs to treat various retinal diseases remains speculative, recent studies highlight that vision restoration strategies are very likely to benefit from the thermo- and mechanosensitive properties of TRPs. This minireview focuses on the evidence of the past 5 years about the role of TRPs in the retina and retinal circulation, raises some possibilities about the function of TRPs in the retina, and discusses the potential sources of endogenous stimuli for TRPs in this tissue, as a reflection for future studies.
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Affiliation(s)
- Stéphanie Thébault
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, 76230 Querétaro, Mexico.
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11
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Transcriptome Analysis of Pterygium and Pinguecula Reveals Evidence of Genomic Instability Associated with Chronic Inflammation. Int J Mol Sci 2021; 22:ijms222112090. [PMID: 34769520 PMCID: PMC8584501 DOI: 10.3390/ijms222112090] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/03/2021] [Accepted: 11/03/2021] [Indexed: 12/24/2022] Open
Abstract
Solar damage due to ultraviolet radiation (UVR) is implicated in the development of two proliferative lesions of the ocular surface: pterygium and pinguecula. Pterygium and pinguecula specimens were collected, along with adjacent healthy conjunctiva specimens. RNA was extracted and sequenced. Pairwise comparisons were made of differentially expressed genes (DEGs). Computational methods were used for analysis. Transcripts from 18,630 genes were identified. Comparison of two subgroups of pterygium specimens uncovered evidence of genomic instability associated with inflammation and the immune response; these changes were also observed in pinguecula, but to a lesser extent. Among the top DEGs were four genes encoding tumor suppressors that were downregulated in pterygium: C10orf90, RARRES1, DMBT1 and SCGB3A1; C10orf90 and RARRES1 were also downregulated in pinguecula. Ingenuity Pathway Analysis overwhelmingly linked DEGs to cancer for both lesions; however, both lesions are clearly still benign, as evidenced by the expression of other genes indicating their well-differentiated and non-invasive character. Pathways for epithelial cell proliferation were identified that distinguish the two lesions, as well as genes encoding specific pathway components. Upregulated DEGs common to both lesions, including KRT9 and TRPV3, provide a further insight into pathophysiology. Our findings suggest that pterygium and pinguecula, while benign lesions, are both on the pathological pathway towards neoplastic transformation.
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12
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Wan SJ, Datta A, Flandrin O, Metruccio MME, Ma S, Nieto V, Kroken AR, Hill RZ, Bautista DM, Evans DJ, Fleiszig SMJ. Nerve-associated transient receptor potential ion channels can contribute to intrinsic resistance to bacterial adhesion in vivo. FASEB J 2021; 35:e21899. [PMID: 34569661 DOI: 10.1096/fj.202100874r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/05/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022]
Abstract
The cornea of the eye differs from other mucosal surfaces in that it lacks a viable bacterial microbiome and by its unusually high density of sensory nerve endings. Here, we explored the role of corneal nerves in preventing bacterial adhesion. Pharmacological and genetic methods were used to inhibit the function of corneal sensory nerves or their associated transient receptor potential cation channels TRPA1 and TRPV1. Impacts on bacterial adhesion, resident immune cells, and epithelial integrity were examined using fluorescent labeling and quantitative confocal imaging. TRPA1/TRPV1 double gene-knockout mice were more susceptible to adhesion of environmental bacteria and to that of deliberately-inoculated Pseudomonas aeruginosa. Supporting the involvement of TRPA1/TRPV1-expressing corneal nerves, P. aeruginosa adhesion was also promoted by treatment with bupivacaine, or ablation of TRPA1/TRPV1-expressing nerves using RTX. Moreover, TRPA1/TRPV1-dependent defense was abolished by enucleation which severs corneal nerves. High-resolution imaging showed normal corneal ultrastructure and surface-labeling by wheat-germ agglutinin for TRPA1/TRPV1 knockout murine corneas, and intact barrier function by absence of fluorescein staining. P. aeruginosa adhering to corneas after perturbation of nerve or TRPA1/TRPV1 function failed to penetrate the surface. Single gene-knockout mice showed roles for both TRPA1 and TRPV1, with TRPA1-/- more susceptible to P. aeruginosa adhesion while TRPV1-/- corneas instead accumulated environmental bacteria. Corneal CD45+/CD11c+ cell responses to P. aeruginosa challenge, previously shown to counter bacterial adhesion, also depended on TRPA1/TRPV1 and sensory nerves. Together, these results demonstrate roles for corneal nerves and TRPA1/TRPV1 in corneal resistance to bacterial adhesion in vivo and suggest that the mechanisms involve resident immune cell populations.
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Affiliation(s)
- Stephanie J Wan
- Vision Science Program, University of California, Berkeley, California, USA
| | - Ananya Datta
- School of Optometry, University of California, Berkeley, California, USA
| | - Orneika Flandrin
- Vision Science Program, University of California, Berkeley, California, USA
| | | | - Sophia Ma
- School of Optometry, University of California, Berkeley, California, USA
| | - Vincent Nieto
- School of Optometry, University of California, Berkeley, California, USA
| | - Abby R Kroken
- School of Optometry, University of California, Berkeley, California, USA
| | - Rose Z Hill
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - Diana M Bautista
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, California, USA.,College of Pharmacy, Touro University California, Vallejo, California, USA
| | - Suzanne M J Fleiszig
- Vision Science Program, University of California, Berkeley, California, USA.,School of Optometry, University of California, Berkeley, California, USA.,Graduate Groups in Microbiology and Infectious Diseases & Immunity, University of California, Berkeley, California, USA
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13
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Chigbu DI, Labib BA. Immunopharmacology in Vernal Keratoconjunctivitis: Current and Future Perspectives. Pharmaceuticals (Basel) 2021; 14:ph14070658. [PMID: 34358085 PMCID: PMC8308551 DOI: 10.3390/ph14070658] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 06/24/2021] [Accepted: 06/29/2021] [Indexed: 12/27/2022] Open
Abstract
Vernal keratoconjunctivitis (VKC) is a complex and chronic, multifactorial Th2 cell-mediated chronic ocular surface inflammatory condition that typically affects predominantly male children in hot or warm climates. The primary symptom is intense ocular pruritus, often significant enough to affect activities of daily living. Clinical features differ from simple forms of allergic conjunctivitis in that they are more-or-less confined to the superior tarsus and limbus. There is also a risk of corneal involvement, which leads to irreversible vision loss in approximately 6% of patients. Right now, there is no standardized treatment protocol, and many of the currently available options are not effective in severe and recurrent cases. As such, it is imperative to understand this complex allergic immune response in order to identify future therapeutic targets. This review will focus on potential drug targets in VKC, with particular emphasis on immunomodulators and immunobiologic agents.
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14
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Jiao H, Ivanusic JJ, McMenamin PG, Chinnery HR. Distribution of Corneal TRPV1 and Its Association With Immune Cells During Homeostasis and Injury. Invest Ophthalmol Vis Sci 2021; 62:6. [PMID: 34232260 PMCID: PMC8267209 DOI: 10.1167/iovs.62.9.6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Purpose Given the role of corneal sensory nerves during epithelial wound repair, we sought to examine the relationship between immune cells and polymodal nociceptors following corneal injury. Methods Young C57BL/6J mice received a 2 mm corneal epithelial injury. One week later, corneal wholemounts were immunostained using β-tubulin-488, TRPV1 (transient receptor potential ion channel subfamily V member-1, a nonselective cation channel) and immune cell (MHC-II, CD45 and CD68) antibodies. The sum length of TRPV1+ and TRPV1– nerve fibers, and their spatial association with immune cells, was quantified in intact and injured corneas. Results TRPV1+ nerves account for ∼40% of the nerve fiber length in the intact corneal epithelium and ∼80% in the stroma. In the superficial epithelial layers, TRPV1+ nerve terminal length was similar in injured and intact corneas. In intact corneas, the density (sum length) of basal epithelial TRPV1+ and TRPV1− nerve fibers was similar, however, in injured corneas, TRPV1+ nerve density was higher compared to TRPV1− nerves. The degree of physical association between TRPV1+ nerves and intraepithelial CD45+ MHC-II+ CD11c+ cells was similar in intact and injured corneas. Stromal leukocytes co-expressed TRPV1, which was partially localized to CD68+ lysosomes, and this expression pattern was lower in injured corneas. Conclusions TRPV1+ nerves accounted for a higher proportion of corneal nerves after injury, which may provide insights into the pathophysiology of neuropathic pain following corneal trauma. The close interactions of TRPV1+ nerves with intraepithelial immune cells and expression of TRPV1 by stromal macrophages provide evidence of neuroimmune interactions in the cornea.
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Affiliation(s)
- Haihan Jiao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Australia.,Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Jason J Ivanusic
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Paul G McMenamin
- Department of Anatomy & Developmental Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Australia
| | - Holly R Chinnery
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Australia
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15
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Martinez-Carrasco R, Argüeso P, Fini ME. Membrane-associated mucins of the human ocular surface in health and disease. Ocul Surf 2021; 21:313-330. [PMID: 33775913 PMCID: PMC8328898 DOI: 10.1016/j.jtos.2021.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/02/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023]
Abstract
Mucins are a family of high molecular weight, heavily-glycosylated proteins produced by wet epithelial tissues, including the ocular surface epithelia. Densely-packed O-linked glycan chains added post-translationally confer the biophysical properties of hydration, lubrication, anti-adhesion and repulsion. Membrane-associated mucins (MAMs) are the distinguishing components of the mucosal glycocalyx. At the ocular surface, MAMs maintain wetness, lubricate the blink, stabilize the tear film, and create a physical barrier to the outside world. In addition, it is increasingly appreciated that MAMs function as cell surface receptors that transduce information from the outside to the inside of the cell. Recently, our team published a comprehensive review/perspectives article for molecular scientists on ocular surface MAMs, including previously unpublished data and analyses on two new genes MUC21 and MUC22, as well as new MAM functions and biological roles, comparing human and mouse (PMID: 31493487). The current article is a refocus for the audience of The Ocular Surface. First, we update the gene and protein information in a more concise form, and include a new section on glycosylation. Next, we discuss biological roles, with some new sections and further updating from our previous review. Finally, we provide a new chapter on MAM involvement in ocular surface disease. We end this with discussion of an emerging mechanism responsible for damage to the epithelia and their mucosal glycocalyces: the unfolded protein response (UPR). The UPR offers a novel target for therapeutic intervention.
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Affiliation(s)
- Rafael Martinez-Carrasco
- Department of Ophthalmology, Tufts University School of Medicine at New England Eye Center, Tufts Medical Center, Boston, MA, 02111, USA.
| | - Pablo Argüeso
- Department of Ophthalmology, Harvard Medical School at Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, 02114, USA.
| | - M Elizabeth Fini
- Department of Ophthalmology, Tufts University School of Medicine at New England Eye Center, Tufts Medical Center: Program in Pharmacology & Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, MA, O2111, USA.
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16
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Mesquita G, Prevarskaya N, Schwab A, Lehen’kyi V. Role of the TRP Channels in Pancreatic Ductal Adenocarcinoma Development and Progression. Cells 2021; 10:cells10051021. [PMID: 33925979 PMCID: PMC8145744 DOI: 10.3390/cells10051021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/18/2021] [Accepted: 04/21/2021] [Indexed: 12/28/2022] Open
Abstract
The transient receptor potential channels (TRPs) have been related to several different physiologies that range from a role in sensory physiology (including thermo- and osmosensation) to a role in some pathologies like cancer. The great diversity of functions performed by these channels is represented by nine sub-families that constitute the TRP channel superfamily. From the mid-2000s, several reports have shown the potential role of the TRP channels in cancers of multiple origin. The pancreatic cancer is one of the deadliest cancers worldwide. Its prevalence is predicted to rise further. Disappointingly, the treatments currently used are ineffective. There is an urgency to find new ways to counter this disease and one of the answers may lie in the ion channels belonging to the superfamily of TRP channels. In this review, we analyse the existing knowledge on the role of TRP channels in the development and progression of pancreatic ductal adenocarcinoma (PDAC). The functions of these channels in other cancers are also considered. This might be of interest for an extrapolation to the pancreatic cancer in an attempt to identify potential therapeutic interventions.
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Affiliation(s)
- Gonçalo Mesquita
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channels Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, 59650 Villeneuve d’Ascq, France; (G.M.); (N.P.)
- PHYCELL—Laboratoire de Physiologie Cellulaire, INSERM U1003, University of Lille, 59655 Villeneuve d’Ascq, France
- Institute of Physiology II, University Münster, 48149 Münster, Germany;
| | - Natalia Prevarskaya
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channels Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, 59650 Villeneuve d’Ascq, France; (G.M.); (N.P.)
- PHYCELL—Laboratoire de Physiologie Cellulaire, INSERM U1003, University of Lille, 59655 Villeneuve d’Ascq, France
| | - Albrecht Schwab
- Institute of Physiology II, University Münster, 48149 Münster, Germany;
| | - V’yacheslav Lehen’kyi
- Laboratory of Cell Physiology, INSERM U1003, Laboratory of Excellence Ion Channels Science and Therapeutics, Department of Biology, Faculty of Science and Technologies, University of Lille, 59650 Villeneuve d’Ascq, France; (G.M.); (N.P.)
- PHYCELL—Laboratoire de Physiologie Cellulaire, INSERM U1003, University of Lille, 59655 Villeneuve d’Ascq, France
- Correspondence: ; Tel.: +33-(0)-3-20-33-70-78; Fax: +33-(0)-3-20-43-40-66
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17
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Guarino BD, Paruchuri S, Thodeti CK. The role of TRPV4 channels in ocular function and pathologies. Exp Eye Res 2020; 201:108257. [PMID: 32979394 DOI: 10.1016/j.exer.2020.108257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022]
Abstract
Transient potential receptor vanilloid 4 (TRPV4) is an ion channel responsible for sensing osmotic and mechanical signals, which in turn regulates calcium signaling across cell membranes. TRPV4 is widely expressed throughout the body, and plays an important role in normal physiological function, as well as different pathologies, however, its role in the eye is not well known. In the eye, TRPV4 is expressed in various tissues, such as the retina, corneal epithelium, ciliary body, and the lens. In this review, we provide an overview on TRPV4 structure, activation, mutations, and summarize the current knowledge of TRPV4 function and signaling mechanisms in various locations throughout the eye, as well as its role in ocular diseases, such as glaucoma and diabetic retinopathy. Based on the available data, we highlight the therapeutic potential of TRPV4 as well as the shortcomings of current research. Finally, we provide future perspectives on the implications of targeting TRPV4 to treat various ocular pathologies.
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Affiliation(s)
- Brianna D Guarino
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | | | - Charles K Thodeti
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.
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18
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Lapajne L, Lakk M, Yarishkin O, Gubeljak L, Hawlina M, Križaj D. Polymodal Sensory Transduction in Mouse Corneal Epithelial Cells. Invest Ophthalmol Vis Sci 2020; 61:2. [PMID: 32271891 PMCID: PMC7401707 DOI: 10.1167/iovs.61.4.2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Contact lenses, osmotic stressors, and chemical burns may trigger severe discomfort and vision loss by damaging the cornea, but the signaling mechanisms used by corneal epithelial cells (CECs) to sense extrinsic stressors are not well understood. We therefore investigated the mechanisms of swelling, temperature, strain, and chemical transduction in mouse CECs. Methods Intracellular calcium imaging in conjunction with electrophysiology, pharmacology, transcript analysis, immunohistochemistry, and bioluminescence assays of adenosine triphosphate (ATP) release were used to track mechanotransduction in dissociated CECs and epithelial sheets isolated from the mouse cornea. Results The transient receptor potential vanilloid (TRPV) transcriptome in the mouse corneal epithelium is dominated by Trpv4, followed by Trpv2, Trpv3, and low levels of Trpv1 mRNAs. TRPV4 protein was localized to basal and intermediate epithelial strata, keratocytes, and the endothelium in contrast to the cognate TRPV1, which was confined to intraepithelial afferents and a sparse subset of CECs. The TRPV4 agonist GSK1016790A induced cation influx and calcium elevations, which were abolished by the selective blocker HC067047. Hypotonic solutions, membrane strain, and moderate heat elevated [Ca2+]CEC with swelling- and temperature-, but not strain-evoked signals, sensitive to HC067047. GSK1016790A and swelling evoked calcium-dependent ATP release, which was suppressed by HC067027 and the hemichannel blocker probenecid. Conclusions These results demonstrate that cation influx via TRPV4 transduces osmotic and thermal but not strain inputs to CECs and promotes hemichannel-dependent ATP release. The TRPV4-hemichannel-ATP signaling axis might modulate corneal pain induced by excessive mechanical, osmotic, and chemical stimulation.
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19
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Genomic analysis of 21 patients with corneal neuralgia after refractive surgery. Pain Rep 2020; 5:e826. [PMID: 32766464 PMCID: PMC7390595 DOI: 10.1097/pr9.0000000000000826] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/13/2020] [Indexed: 12/19/2022] Open
Abstract
Background Refractive surgery, specifically laser-assisted in situ keratomileusis and photorefractive keratectomy, are widely applied procedures to treat myopia, hyperopia, and astigmatism. After surgery, a subgroup of cases suffers from persistent and intractable pain of obscure etiology, thought to be neuropathic. We aimed to investigate the contribution of genomic factors in the pathogenesis of these patients with corneal neuralgia. Methods We enrolled 21 cases (6 males and 15 females) from 20 unrelated families, who reported persistent pain (>3 months), after refractive surgery (20 laser-assisted in situ keratomileusis and 1 photorefractive keratectomy patients). Whole-exome sequencing and gene-based association test were performed. Results Whole-exome sequencing demonstrated low-frequency variants (allele frequency < 0.05) in electrogenisome-related ion channels and cornea-expressed collagens, most frequently in SCN10A (5 cases), SCN9A (4 cases), TRPV1 (4 cases), CACNA1H and CACNA2D2 (5 cases each), COL5A1 (6 cases), COL6A3 (5 cases), and COL4A2 (4 cases). Two variants, p.K655R of SCN9A and p.Q85R of TRPV1, were previously characterized as gain-of-function. Gene-based association test assessing "damaging" missense variants against gnomAD exome database (non-Finnish European or global), identified a gene, SLC9A3R1, with statistically significant effect (odds ratio = 17.09 or 17.04; Bonferroni-corrected P-value < 0.05). Conclusion These findings in a small patient cohort did not identify a common gene/variant among most of these cases, as found in other disorders, for example small-fiber neuropathy. Further studies of these candidate genes/variants might enhance understanding of the role of genetic factors in the pathogenesis of corneal neuralgia.
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20
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Irnaten M, O'Malley G, Clark AF, O'Brien CJ. Transient receptor potential channels TRPC1/TRPC6 regulate lamina cribrosa cell extracellular matrix gene transcription and proliferation. Exp Eye Res 2020; 193:107980. [PMID: 32088241 DOI: 10.1016/j.exer.2020.107980] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 01/13/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023]
Abstract
The lamina cribrosa (LC) in glaucoma is with augmented production of extracellular matrix proteins (ECM) and connective tissue fibrosis. Fundamental pathological mechanisms for this fibrosis comprise fibrotic growth factors and oxidative stress. Transient receptor potential canonical channels (TRPC) channels play a key role in ECM fibrosis. Here, we study TRPC expression in glaucomatous LC cells, and investigate the role of TRPC in oxidative stress induced-profibrotic ECM gene transcription and cell proliferation in normal LC cells. Age-matched human LC cells (normal, n = 3 donors; glaucoma, n = 3 donors) were used. Hydrogen peroxide (H2O2, 100 μM), was used to induce oxidative stress in LC cells in the presence or absence of the pan TRPC inhibitor SKF96365 (10 μM) or knockdown of TRPC1/6 with siRNA. After treatments, ECM gene transcription, LC cell viability and proliferation and the phosphorylation of the transcription factor NFATc3, were measured using real time RT-PCR, colorimetric cell counting with the methyl-thiazolyl tetrazolium salt (MTS) assay, and Western immunoblotting, respectively. Results showed that TRPC1/C6 transcript and protein expression levels were significantly (p < 0.05) enhanced in glaucoma LC cells. Both SKF96365 and siRNA-TRPC1/C6 treatments significantly reduced the oxidative stress induced-ECM gene expression (transforming growth factor-β1 (TGFβ1), alpha smooth muscle actin (α-SMA), and collagen type 1A1 (Col1A1)), and cell proliferation in normal and glaucoma LC cells. Also, SKF96365 treatment inhibited the H2O2-induced NFATc3 protein dephosphorylation in LC cells. In conclusion, TRPC1/C6 expression is enhanced in glaucoma LC cells. These channels may contribute to oxidative stress-induced ECM gene transcription and cell proliferation in normal and glaucoma LC cells through Ca2+-NFATc3 signaling pathway mechanism. TRPC1 and TRPC6 channels could be important therapeutic targets to prevent ECM remodeling and fibrosis development in glaucoma optic neuropathy.
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Affiliation(s)
- M Irnaten
- Department of Ophthalmology, Mater Misericordiae Hospital, Dublin 7, Ireland; School of Medicine, University College Dublin, Dublin 4, Ireland.
| | - G O'Malley
- School of Medicine, University College Dublin, Dublin 4, Ireland
| | - A F Clark
- Dept. Pharmacology & Neuroscience and the North Texas Eye Research Institute, U. North Texas, Health Science Centre, Ft Worth, TX, USA
| | - C J O'Brien
- Department of Ophthalmology, Mater Misericordiae Hospital, Dublin 7, Ireland; School of Medicine, University College Dublin, Dublin 4, Ireland
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21
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Fini ME, Jeong S, Gong H, Martinez-Carrasco R, Laver NMV, Hijikata M, Keicho N, Argüeso P. Membrane-associated mucins of the ocular surface: New genes, new protein functions and new biological roles in human and mouse. Prog Retin Eye Res 2019; 75:100777. [PMID: 31493487 DOI: 10.1016/j.preteyeres.2019.100777] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/26/2019] [Accepted: 08/31/2019] [Indexed: 01/17/2023]
Abstract
The mucosal glycocalyx of the ocular surface constitutes the point of interaction between the tear film and the apical epithelial cells. Membrane-associated mucins (MAMs) are the defining molecules of the glycocalyx in all mucosal epithelia. Long recognized for their biophysical properties of hydration, lubrication, anti-adhesion and repulsion, MAMs maintain the wet ocular surface, lubricate the blink, stabilize the tear film and create a physical barrier to the outside world. However, it is increasingly appreciated that MAMs also function as cell surface receptors that transduce information from the outside to the inside of the cell. A number of excellent review articles have provided perspective on the field as it has progressed since 1987, when molecular cloning of the first MAM was reported. The current article provides an update for the ocular surface, placing it into the broad context of findings made in other organ systems, and including new genes, new protein functions and new biological roles. We discuss the epithelial tissue-equivalent with mucosal differentiation, the key model system making these advances possible. In addition, we make the first systematic comparison of MAMs in human and mouse, establishing the basis for using knockout mice for investigations with the complexity of an in vivo system. Lastly, we discuss findings from human genetics/genomics, which are providing clues to new MAM roles previously unimagined. Taken together, this information allows us to generate hypotheses for the next stage of investigation to expand our knowledge of MAM function in intracellular signaling and roles unique to the ocular surface.
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Affiliation(s)
- M Elizabeth Fini
- Department of Ophthalmology, Tufts University School of Medicine, at New England Eye Center, Tufts Medical Center, 800 Washington St, Boston, MA, 02111, USA.
| | - Shinwu Jeong
- USC Roski Eye Institute and Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, 1975 Zonal Ave, Los Angeles, CA, 90033, USA.
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, 72 E Concord St, Boston, MA, 02118, USA.
| | - Rafael Martinez-Carrasco
- Department of Ophthalmology, Tufts University School of Medicine, at New England Eye Center, Tufts Medical Center, 800 Washington St, Boston, MA, 02111, USA.
| | - Nora M V Laver
- Department of Ophthalmology, Tufts University School of Medicine, at New England Eye Center, Tufts Medical Center, 800 Washington St, Boston, MA, 02111, USA.
| | - Minako Hijikata
- Department of Pathophysiology and Host Defense, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, 3-1-24 Matsuyama, Kiyose-shi, Tokyo, 204-8533, Japan.
| | - Naoto Keicho
- Department of Pathophysiology and Host Defense, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, 3-1-24 Matsuyama, Kiyose-shi, Tokyo, 204-8533, Japan.
| | - Pablo Argüeso
- Department of Ophthalmology, Harvard Medical School, at Schepens Eye Research Institute of Mass. Eye and Ear, 20 Staniford St, Boston, MA, 02114, USA.
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22
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23
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Hatta A, Kurose M, Sullivan C, Okamoto K, Fujii N, Yamamura K, Meng ID. Dry eye sensitizes cool cells to capsaicin-induced changes in activity via TRPV1. J Neurophysiol 2019; 121:2191-2201. [PMID: 30969886 DOI: 10.1152/jn.00126.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Corneal cool cells are sensitive to the ocular fluid status of the corneal surface and may be responsible for the regulation of basal tear production. Previously, we have shown that dry eye, induced by lacrimal gland excision (LGE) in rats, sensitized corneal cool cells to the transient receptor potential melastatin 8 (TRPM8) agonist menthol and to cool stimulation. In the present study, we examined the effect of dry eye on the sensitivity of cool cells to the transient receptor potential vanilloid 1 (TRPV1) agonist capsaicin. Single-unit recordings in the trigeminal ganglion were performed 7-10 days after LGE. At a concentration of 0.3 μM, capsaicin did not affect ongoing or cool-evoked activity in control animals yet facilitated ongoing activity and suppressed cool-evoked activity in LGE animals. At higher concentrations (3 μM), capsaicin continued to facilitate ongoing activity in LGE animals but suppressed ongoing activity in control animals. Higher concentrations of capsaicin also suppressed cool-evoked activity in both groups of animals, with an overall greater effect in LGE animals. In addition to altering cool-evoked activity, capsaicin enhanced the sensitivity of cool cells to heat in LGE animals. Capsaicin-induced changes were prevented by the application of the TRPV1 antagonist capsazepine. With the use of fluorescent in situ hybridization, TRPV1 and TRPM8 expression was examined in retrograde tracer-identified corneal neurons. The coexpression of TRPV1 and TRPM8 in corneal neurons was significantly greater in LGE-treated animals when compared with sham controls. These results indicate that LGE-induced dry eye increases TRPV1-mediated responses in corneal cool cells at least in part through the increased expression of TRPV1. NEW & NOTEWORTHY Corneal cool cells are known to detect drying of the ocular surface. Our study is the first to report that dry eye induced alterations in cool cell response properties, including the increased responsiveness to noxious heat and activation by capsaicin. Along with the changes in cell response properties, it is possible these neurons also function differently in dry eye, relaying information related to the perception of ocular irritation in addition to regulating tearing and blinking.
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Affiliation(s)
- Azusa Hatta
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan.,General Dentistry and Clinical Education Unit, Niigata University Medical and Dental Hospital , Niigata , Japan
| | - Masayuki Kurose
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan
| | - Cara Sullivan
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine.,Graduate Studies in Biomedical Sciences and Engineering, University of Maine , Orono, Maine
| | - Keiichiro Okamoto
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan
| | - Noritaka Fujii
- General Dentistry and Clinical Education Unit, Niigata University Medical and Dental Hospital , Niigata , Japan
| | - Kensuke Yamamura
- Division of Oral Physiology, Department of Oral Biological Sciences, Niigata University, Graduate School of Medical and Dental Sciences , Niigata , Japan
| | - Ian D Meng
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine
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24
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TRPM8 Channels and Dry Eye. Pharmaceuticals (Basel) 2018; 11:ph11040125. [PMID: 30445735 PMCID: PMC6316058 DOI: 10.3390/ph11040125] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 11/05/2018] [Accepted: 11/12/2018] [Indexed: 12/17/2022] Open
Abstract
Transient receptor potential (TRP) channels transduce signals of chemical irritation and temperature change from the ocular surface to the brain. Dry eye disease (DED) is a multifactorial disorder wherein the eyes react to trivial stimuli with abnormal sensations, such as dryness, blurring, presence of foreign body, discomfort, irritation, and pain. There is increasing evidence of TRP channel dysfunction (i.e., TRPV1 and TRPM8) in DED pathophysiology. Here, we review some of this literature and discuss one strategy on how to manage DED using a TRPM8 agonist.
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25
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Shahidullah M, Mandal A, Delamere NA. Activation of TRPV1 channels leads to stimulation of NKCC1 cotransport in the lens. Am J Physiol Cell Physiol 2018; 315:C793-C802. [PMID: 30207782 DOI: 10.1152/ajpcell.00252.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lens ion homeostasis is crucial in maintaining water content and, in turn, refractive index and transparency of the multicellular syncytium-like structure. New information is emerging on the regulation of ion transport in the lens by mechanisms that rely on transient receptor potential vanilloid (TRPV) ion channels. We found recently that TRPV1 activation leads to Ca2+/PKC-dependent ERK1/2 signaling. Here, we show that the TRPV1 agonist capsaicin (100 nM) and hyperosmotic solution (350 vs. 300 mosM) each caused an increase of bumetanide-inhibitable Rb uptake by intact porcine lenses and Na-K-2Cl cotransporter 1 (NKCC1) phosphorylation in the lens epithelium. The TRPV1 antagonist A889425 (1 µM) abolished the increases of Rb uptake and NKCC1 phosphorylation in response to hyperosmotic solution. Exposing lenses to hyperosmotic solution in the presence of MEK/ERK inhibitor U0126 (10 µM) or the with-no-lysine kinase (WNK) inhibitor WNK463 (1 µM) also prevented NKCC1 phosphorylation and the Rb uptake responses to hyperosmotic solution. WNK463 did not prevent the increase in ERK1/2 phosphorylation that occurs in response to capsaicin or hyperosmotic solution, suggesting that ERK1/2 activation occurs before WNK activation in the sequence of signaling events. Taken together, the evidence indicates that activation of TRPV1 is a critical early step in a signaling mechanism that responds to a hyperosmotic stimulus, possibly lens shrinkage. By activating ERK1/2 and WNK, TRPV1 activation leads to NKCC1 phosphorylation and stimulation of NKCC1-mediated ion transport.
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Affiliation(s)
- Mohammad Shahidullah
- Department of Physiology, University of Arizona , Tucson, Arizona.,Department of Ophthalmology and Vision Science, University of Arizona , Tucson, Arizona
| | - Amritlal Mandal
- Department of Physiology, University of Arizona , Tucson, Arizona
| | - Nicholas A Delamere
- Department of Physiology, University of Arizona , Tucson, Arizona.,Department of Ophthalmology and Vision Science, University of Arizona , Tucson, Arizona
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Bräunig J, Mergler S, Jyrch S, Hoefig CS, Rosowski M, Mittag J, Biebermann H, Khajavi N. 3-Iodothyronamine Activates a Set of Membrane Proteins in Murine Hypothalamic Cell Lines. Front Endocrinol (Lausanne) 2018; 9:523. [PMID: 30298050 PMCID: PMC6161562 DOI: 10.3389/fendo.2018.00523] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/21/2018] [Indexed: 01/26/2023] Open
Abstract
3-Iodothyronamine (3-T1AM) is an endogenous thyroid hormone metabolite. The profound pharmacological effects of 3-T1AM on energy metabolism and thermal homeostasis have raised interest to elucidate its signaling properties in tissues that pertain to metabolic regulation and thermogenesis. Previous studies identified G protein-coupled receptors (GPCRs) and transient receptor potential channels (TRPs) as targets of 3-T1AM in different cell types. These two superfamilies of membrane proteins are largely expressed in tissue which influences energy balance and metabolism. As the first indication that 3-T1AM virtually modulates the function of the neurons in hypothalamus, we observed that intraperitoneal administration of 50 mg/kg bodyweight of 3-T1AM significantly increased the c-FOS activation in the paraventricular nucleus (PVN) of C57BL/6 mice. To elucidate the underlying mechanism behind this 3-T1AM-induced signalosome, we used three different murine hypothalamic cell lines, which are all known to express PVN markers, GT1-7, mHypoE-N39 (N39) and mHypoE-N41 (N41). Various aminergic GPCRs, which are the known targets of 3-T1AM, as well as numerous members of TRP channel superfamily, are expressed in these cell lines. Effects of 3-T1AM on activation of GPCRs were tested for the two major signaling pathways, the action of Gαs/adenylyl cyclase and Gi/o. Here, we demonstrated that this thyroid hormone metabolite has no significant effect on Gi/o signaling and only a minor effect on the Gαs/adenylyl cyclase pathway, despite the expression of known GPCR targets of 3-T1AM. Next, to test for other potential mechanisms involved in 3-T1AM-induced c-FOS activation in PVN, we evaluated the effect of 3-T1AM on the intracellular Ca2+ concentration and whole-cell currents. The fluorescence-optic measurements showed a significant increase of intracellular Ca2+ concentration in the three cell lines in the presence of 10 μM 3-T1AM. Furthermore, this thyroid hormone metabolite led to an increase of whole-cell currents in N41 cells. Interestingly, the TRPM8 selective inhibitor (10 μM AMTB) reduced the 3-T1AM stimulatory effects on cytosolic Ca2+ and whole-cell currents. Our results suggest that the profound pharmacological effects of 3-T1AM on selected brain nuclei of murine hypothalamus, which are known to be involved in energy metabolism and thermoregulation, might be partially attributable to TRP channel activation in hypothalamic cells.
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Affiliation(s)
- Julia Bräunig
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Stefan Mergler
- Klinik für Augenheilkunde, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sabine Jyrch
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Carolin S. Hoefig
- Institute of Experimental Endocrinology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Department of Cell & Molecular Biology, Karolinska Instituet, Stockholm, Sweden
| | - Mark Rosowski
- Department Medical Biotechnology, Institute of Biotechnology, Technical University of Berlin, Berlin, Germany
| | - Jens Mittag
- Department of Cell & Molecular Biology, Karolinska Instituet, Stockholm, Sweden
- University of Lübeck – Center of Brain Behavior and Metabolism, Lübeck, Germany
| | - Heike Biebermann
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Noushafarin Khajavi
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Institute of Experimental Pediatric Endocrinology, Berlin, Germany
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Abstract
PURPOSE OF REVIEW This review aims to describe the recent findings on epidemiology, pathophysiology, and management of neuropathic symptoms of the ocular surface, with a focus on potential similarities between sensations of dry eye, pain and itch. RECENT FINDINGS A narrative review of the literature was undertaken. Key references from research in dry eye, neuropathic symptoms of the ocular surface, ocular pain and itch, as well as general references on itch and pain neurobiology were included. Recent findings suggest aspects of dry eye, chronic ocular pain and itch symptomatology are driven by neuropathic pain mechanisms involving peripheral and central sensitization processes. SUMMARY Ocular dryness, pain, and itch are prevalent complaints with several of shared features. Multiple lines of evidence suggest that peripheral and central neuronal sensitization processes are involved in generating and maintaining ocular sensory symptoms. Research is warranted on the epidemiology of ocular sensations, molecular mechanisms involved in nociception and pruriception in the eye, electrophysiological alterations in animal models of eye conditions, and therapeutic modalities that can alleviate unpleasant ocular sensations.
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Türker E, Garreis F, Khajavi N, Reinach PS, Joshi P, Brockmann T, Lucius A, Ljubojevic N, Turan E, Cooper D, Schick F, Reinholz R, Pleyer U, Köhrle J, Mergler S. Vascular Endothelial Growth Factor (VEGF) Induced Downstream Responses to Transient Receptor Potential Vanilloid 1 (TRPV1) and 3-Iodothyronamine (3-T 1AM) in Human Corneal Keratocytes. Front Endocrinol (Lausanne) 2018; 9:670. [PMID: 30524369 PMCID: PMC6262029 DOI: 10.3389/fendo.2018.00670] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/26/2018] [Indexed: 12/30/2022] Open
Abstract
This study was undertaken to determine if crosstalk among the transient receptor potential (TRP) melastatin 8 (TRPM8), TRP vanilloid 1 (TRPV1), and vascular endothelial growth factor (VEGF) receptor triad modulates VEGF-induced Ca2+ signaling in human corneal keratocytes. Using RT-PCR, qPCR and immunohistochemistry, we determined TRPV1 and TRPM8 gene and protein coexpression in a human corneal keratocyte cell line (HCK) and human corneal cross sections. Fluorescence Ca2+ imaging using both a photomultiplier and a single cell digital imaging system as well as planar patch-clamping measured relative intracellular Ca2+ levels and underlying whole-cell currents. The TRPV1 agonist capsaicin increased both intracellular Ca2+ levels and whole-cell currents, while the antagonist capsazepine (CPZ) inhibited them. VEGF-induced Ca2+ transients and rises in whole-cell currents were suppressed by CPZ, whereas a selective TRPM8 antagonist, AMTB, increased VEGF signaling. In contrast, an endogenous thyroid hormone-derived metabolite 3-Iodothyronamine (3-T1AM) suppressed increases in the VEGF-induced current. The TRPM8 agonist menthol increased the currents, while AMTB suppressed this response. The VEGF-induced increases in Ca2+ influx and their underlying ionic currents stem from crosstalk between VEGFR and TRPV1, which can be impeded by 3-T1AM-induced TRPM8 activation. Such suppression in turn blocks VEGF-induced TRPV1 activation. Therefore, crosstalk between TRPM8 and TRPV1 inhibits VEGFR-induced activation of TRPV1.
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Affiliation(s)
- Ersal Türker
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Fabian Garreis
- Department of Functional and Clinical Anatomy, Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Noushafarin Khajavi
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Walter Straub Institute of Pharmacology and Toxicology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Peter S. Reinach
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Pooja Joshi
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Tobias Brockmann
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Alexander Lucius
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Nina Ljubojevic
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Elizabeth Turan
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Drew Cooper
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Felix Schick
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Rob Reinholz
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Uwe Pleyer
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Stefan Mergler
- Klinik für Augenheilkunde, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- *Correspondence: Stefan Mergler
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29
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Krishnatreyya H, Hazarika H, Saha A, Chattopadhyay P. Capsaicin, the primary constituent of pepper sprays and its pharmacological effects on mammalian ocular tissues. Eur J Pharmacol 2018; 819:114-121. [DOI: 10.1016/j.ejphar.2017.11.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/20/2017] [Accepted: 11/24/2017] [Indexed: 01/07/2023]
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30
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Schwenk M. Chemical warfare agents. Classes and targets. Toxicol Lett 2017; 293:253-263. [PMID: 29197625 DOI: 10.1016/j.toxlet.2017.11.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 12/30/2022]
Abstract
Synthetic toxic chemicals (toxicants) and biological poisons (toxins) have been developed as chemical warfare agents in the last century. At the time of their initial consideration as chemical weapon, only restricted knowledge existed about their mechanisms of action. There exist two different types of acute toxic action: nonspecific cytotoxic mechanisms with multiple chemo-biological interactions versus specific mechanisms that tend to have just a single or a few target biomolecules. TRPV1- and TRPA-receptors are often involved as chemosensors that induce neurogenic inflammation. The present work briefly surveys classes and toxicologically relevant features of chemical warfare agents and describes mechanisms of toxic action.
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Affiliation(s)
- Michael Schwenk
- Formerly: Medical School Hannover. Present address: In den Kreuzäckern 16/1, 72072 Tübingen, Germany.
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31
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TRPV1: A Target for Rational Drug Design. Pharmaceuticals (Basel) 2016; 9:ph9030052. [PMID: 27563913 PMCID: PMC5039505 DOI: 10.3390/ph9030052] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/12/2016] [Accepted: 08/18/2016] [Indexed: 12/18/2022] Open
Abstract
Transient Receptor Potential Vanilloid 1 (TRPV1) is a non-selective, Ca2+ permeable cation channel activated by noxious heat, and chemical ligands, such as capsaicin and resiniferatoxin (RTX). Many compounds have been developed that either activate or inhibit TRPV1, but none of them are in routine clinical practice. This review will discuss the rationale for antagonists and agonists of TRPV1 for pain relief and other conditions, and strategies to develop new, better drugs to target this ion channel, using the newly available high-resolution structures.
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32
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Chen GL, Lei M, Zhou LP, Zeng B, Zou F. Borneol Is a TRPM8 Agonist that Increases Ocular Surface Wetness. PLoS One 2016; 11:e0158868. [PMID: 27448228 PMCID: PMC4957794 DOI: 10.1371/journal.pone.0158868] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/17/2016] [Indexed: 12/12/2022] Open
Abstract
Borneol is a compound widely used in ophthalmic preparations in China. Little is known about its exact role in treating eye diseases. Here we report that transient receptor potential melastatin 8 (TRPM8) channel is a pharmacological target of borneol and mediates its therapeutic effect in the eyes. Ca2+ measurement and electrophysiological recordings revealed that borneol activated TRPM8 channel in a temperature- and dose-dependent manner, which was similar to but less effective than the action of menthol, an established TRPM8 agonist. Borneol significantly increased tear production in guinea pigs without evoking nociceptive responses at 25°C, but failed to induce tear secretion at 35°C. In contrast, menthol evoked tearing response at both 25 and 35°C. TRPM8 channel blockers N-(3-Aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide hydrochloride (AMTB) and N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl)piperazine-1-carboxamide (BCTC) abolished borneol- and menthol-induced tear secretion. Borneol at micromolar concentrations did not affect the viability of human corneal epithelial cells. We conclude that borneol can activate the cold-sensing TRPM8 channel and modestly increase ocular surface wetness, which suggests it is an active compound in ophthalmic preparations and particularly useful in treating dry eye syndrome.
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Affiliation(s)
- Gui-Lan Chen
- Ministry of Education Key Laboratory of Bio-resources and Eco-environment, College of Life Sciences, Sichuan University, Chengdu, China
- Key Laboratory of Medical Electrophysiology, Ministry of Education, and Institute of Cardiovascular Research, Sichuan Medical University, Luzhou, China
| | - Ming Lei
- Key Laboratory of Medical Electrophysiology, Ministry of Education, and Institute of Cardiovascular Research, Sichuan Medical University, Luzhou, China
| | - Lu-Ping Zhou
- Key Laboratory of Medical Electrophysiology, Ministry of Education, and Institute of Cardiovascular Research, Sichuan Medical University, Luzhou, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education, and Institute of Cardiovascular Research, Sichuan Medical University, Luzhou, China
- * E-mail: (BZ); (FZ)
| | - Fangdong Zou
- Ministry of Education Key Laboratory of Bio-resources and Eco-environment, College of Life Sciences, Sichuan University, Chengdu, China
- * E-mail: (BZ); (FZ)
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