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Asiedu K. Neurophysiology of corneal neuropathic pain and emerging pharmacotherapeutics. J Neurosci Res 2024; 102:e25285. [PMID: 38284865 DOI: 10.1002/jnr.25285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/12/2023] [Accepted: 12/02/2023] [Indexed: 01/30/2024]
Abstract
The altered activity generated by corneal neuronal injury can result in morphological and physiological changes in the architecture of synaptic connections in the nervous system. These changes can alter the sensitivity of neurons (both second-order and higher-order projection) projecting pain signals. A complex process involving different cell types, molecules, nerves, dendritic cells, neurokines, neuropeptides, and axon guidance molecules causes a high level of sensory rearrangement, which is germane to all the phases in the pathomechanism of corneal neuropathic pain. Immune cells migrating to the region of nerve injury assist in pain generation by secreting neurokines that ensure nerve depolarization. Furthermore, excitability in the central pain pathway is perpetuated by local activation of microglia in the trigeminal ganglion and alterations of the descending inhibitory modulation for corneal pain arriving from central nervous system. Corneal neuropathic pain may be facilitated by dysfunctional structures in the central somatosensory nervous system due to a lesion, altered synaptogenesis, or genetic abnormality. Understanding these important pathways will provide novel therapeutic insight.
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Affiliation(s)
- Kofi Asiedu
- School of Optometry & Vision Science, University of New South Wales, Sydney, New South Wales, Australia
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2
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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: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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3
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Daras C. Comment on: Examination of the safety and effectiveness of low concentration nitrous oxide anesthesia in cataract surgery. J Cataract Refract Surg 2022; 48:979. [PMID: 35621258 DOI: 10.1097/j.jcrs.0000000000000981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Christos Daras
- From the Johannesburg Eye Hospital, Johannesburg, South Africa
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4
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Sonkodi B, Resch MD, Hortobágyi T. Is the Sex Difference a Clue to the Pathomechanism of Dry Eye Disease? Watch out for the NGF-TrkA-Piezo2 Signaling Axis and the Piezo2 Channelopathy. J Mol Neurosci 2022; 72:1598-1608. [PMID: 35507012 PMCID: PMC9374789 DOI: 10.1007/s12031-022-02015-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/20/2022] [Indexed: 01/11/2023]
Abstract
Dry eye disease (DED) is a multifactorial disorder with recognized pathology, but not entirely known pathomechanism. It is suggested to represent a continuum with neuropathic corneal pain with the paradox that DED is a pain-free disease in most cases, although it is regarded as a pain condition. The current paper puts into perspective that one gateway from physiology to pathophysiology could be a Piezo2 channelopathy, opening the pathway to a potentially quad-phasic non-contact injury mechanism on a multifactorial basis and with a heterogeneous clinical picture. The primary non-contact injury phase could be the pain-free microinjury of the Piezo2 ion channel at the corneal somatosensory nerve terminal. The secondary non-contact injury phase involves harsher corneal tissue damage with C-fiber contribution due to the lost or inadequate intimate cross-talk between somatosensory Piezo2 and peripheral Piezo1. The third injury phase of this non-contact injury is the neuronal sensitization process with underlying repeated re-injury of the Piezo2, leading to the proposed chronic channelopathy. Notably, sensitization may evolve in certain cases in the absence of the second injury phase. Finally, the quadric injury phase is the lingering low-grade neuroinflammation associated with aging, called inflammaging. This quadric phase could clinically initiate or augment DED, explaining why increasing age is a risk factor. We highlight the potential role of the NGF-TrkA axis as a signaling mechanism that could further promote the microinjury of the corneal Piezo2 in a stress-derived hyperexcited state. The NGF-TrkA-Piezo2 axis might explain why female sex represents a risk factor for DED.
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Affiliation(s)
- Balázs Sonkodi
- Department of Health Sciences and Sport Medicine, Hungarian University of Sports Science, Budapest, Hungary.
| | - Miklós D Resch
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary
| | - Tibor Hortobágyi
- Institute of Pathology, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Insitute of Psychiatry Psychology and Neuroscience, King's College London, London, UK.,Center for Age-Related Medicine, SESAM, Stavanger University Hospital, Stavanger, Norway
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García-López C, Gómez-Huertas C, Sánchez-González JM, Borroni D, Rodríguez-Calvo-de-Mora M, Romano V, Rachwani-Anil R, Ramos-López JF, Ortiz-Pérez S, Rocha-de-Lossada C. Opioids and Ocular Surface Pathology; A Literature Review of New Treatments Horizons. J Clin Med 2022; 11:jcm11051424. [PMID: 35268515 PMCID: PMC8911328 DOI: 10.3390/jcm11051424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 12/01/2022] Open
Abstract
This review discusses the role of opioids in the corneal surface and the different pathways and therapeutic methods of management. A literature review was performed using PubMed database. For the database search, the main searching words “opioid” and “topical opioid treatment” were used with the descriptors “cornea”, “ocular surface”, “neuropathic corneal pain”, “corneal sensitivity” and “naltrexone”; original scientific articles and reviews were included to achieve the purpose of the review. The endogenous opioid system has relevant functions in the organism, and in daily use, opioids are used as painkillers. However, these drugs may be employed for other indications as opioid pathways have a wide spectrum. The corneal surface for topical treatment is easily accessible, hence sparing the side effects of systemic opioids. Instillation of opioid antagonist substances, such as naltrexone, increases corneal healing rates and stimulates the division of corneal epithelium cells without deleterious effects. The natural modulation of endogenous opioids controls different forms of pain, including inflammatory and neuropathic pain, both in the ocular surface and in the central nervous system. There are diverse methods in controlling pain using opioids, especially in refractory forms. This review attempts to collect the literature about corneal surface and opioid pathways to provide an overview image and a possible direction of the news treatments.
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Affiliation(s)
- Celia García-López
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - Carmen Gómez-Huertas
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - José-María Sánchez-González
- Department of Physics of Condensed Matter, Optics Area, University of Seville, 41004 Seville, Spain
- Correspondence: ; Tel.: +34-955-42-08-61
| | - Davide Borroni
- Department of Doctoral Studies, Riga Stradins University, LV-1007 Riga, Latvia;
- Cornea Research Unit, ADVALIA Vision, 20145 Milan, Italy
| | - Marina Rodríguez-Calvo-de-Mora
- Department of Ophthalmology, Hospital Regional Universitario de Málaga, 29010 Málaga, Spain;
- Department of Ophthalmology (Qvision), Vithas Almería, 04120 Almería, Spain
| | - Vito Romano
- Department of Eye and Vision Science Ophthalmology, St Paul’s Eye Hospital, Liverpool L7 8XP, UK;
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK
- Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, Ophthalmology Clinic, University of Brescia, 25121 Brescia, Italy
| | | | - Juan-Francisco Ramos-López
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - Santiago Ortiz-Pérez
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
- Department of Surgery, Faculty of Medicine, University of Granada, 18010 Granada, Spain
| | - Carlos Rocha-de-Lossada
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
- Department of Ophthalmology (Qvision), Vithas Almería, 04120 Almería, Spain
- Department of Ophthalmology, Ceuta Medical Center, 51001 Ceuta, Spain
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Degrandmaison J, Rochon-Haché S, Parent JL, Gendron L. Knock-In Mouse Models to Investigate the Functions of Opioid Receptors in vivo. Front Cell Neurosci 2022; 16:807549. [PMID: 35173584 PMCID: PMC8841419 DOI: 10.3389/fncel.2022.807549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/04/2022] [Indexed: 12/28/2022] Open
Abstract
Due to their low expression levels, complex multi-pass transmembrane structure, and the current lack of highly specific antibodies, the assessment of endogenous G protein-coupled receptors (GPCRs) remains challenging. While most of the research regarding their functions was performed in heterologous systems overexpressing the receptor, recent advances in genetic engineering methods have allowed the generation of several unique mouse models. These animals proved to be useful to investigate numerous aspects underlying the physiological functions of GPCRs, including their endogenous expression, distribution, interactome, and trafficking processes. Given their significant pharmacological importance and central roles in the nervous system, opioid peptide receptors (OPr) are often referred to as prototypical receptors for the study of GPCR regulatory mechanisms. Although only a few GPCR knock-in mouse lines have thus far been generated, OPr are strikingly well represented with over 20 different knock-in models, more than half of which were developed within the last 5 years. In this review, we describe the arsenal of OPr (mu-, delta-, and kappa-opioid), as well as the opioid-related nociceptin/orphanin FQ (NOP) receptor knock-in mouse models that have been generated over the past years. We further highlight the invaluable contribution of such models to our understanding of the in vivo mechanisms underlying the regulation of OPr, which could be conceivably transposed to any other GPCR, as well as the limitations, future perspectives, and possibilities enabled by such tools.
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Affiliation(s)
- Jade Degrandmaison
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Département de Médecine, Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Département de Pharmacologie-Physiologie, Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Quebec Network of Junior Pain Investigators, Sherbrooke, QC, Canada
| | - Samuel Rochon-Haché
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Département de Médecine, Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Département de Pharmacologie-Physiologie, Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Quebec Network of Junior Pain Investigators, Sherbrooke, QC, Canada
| | - Jean-Luc Parent
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Département de Médecine, Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Jean-Luc Parent,
| | - Louis Gendron
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Département de Pharmacologie-Physiologie, Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
- Quebec Pain Research Network, Sherbrooke, QC, Canada
- *Correspondence: Louis Gendron,
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Nortey J, Smith D, Seitzman GD, Gonzales JA. Topical Therapeutic Options in Corneal Neuropathic Pain. Front Pharmacol 2022; 12:769909. [PMID: 35173607 PMCID: PMC8841414 DOI: 10.3389/fphar.2021.769909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/28/2021] [Indexed: 11/16/2022] Open
Abstract
Purpose of Review: Corneal neuropathic pain can be difficult to treat, particularly due to its lack of response to standard dry eye therapies. We describe a variety of topical therapeutic options that are available to treat corneal neuropathic pain with a significant or primary peripheral component. We also describe possible mechanisms of action for such topical therapies. Recent Findings: Topical corticosteroids and blood-derived tear preparations can be helpful. Newer therapies, including topical lacosamide and low-dose naltrexone are emerging therapeutic options that may also be considered. Summary: Corneal neuropathic pain with a significant peripheral component may be managed with a variety of topical therapeutic options.
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Affiliation(s)
- Jeremy Nortey
- School of Medicine, University of North Carolina, Chapel Hill, NC, United Statesa
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, CA, United States
| | - David Smith
- A&O Compounding Pharmacy, Vallejo, CA, United States
| | - Gerami D. Seitzman
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, CA, United States
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, United States
| | - John A. Gonzales
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, CA, United States
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, United States
- *Correspondence: John A. Gonzales,
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Giannaccare G, Ghelardini C, Mancini A, Scorcia V, Di Cesare Mannelli L. New Perspectives in the Pathophysiology and Treatment of Pain in Patients with Dry Eye Disease. J Clin Med 2021; 11:108. [PMID: 35011849 DOI: 10.3390/jcm11010108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 12/13/2022] Open
Abstract
Ocular discomfort and eye pain are frequently reported by patients with dry eye disease (DED), and their management remains a real therapeutic challenge for the Ophthalmologist. In DED patients, injury at the level of each structure of the ocular surface can determine variable symptoms, ranging from mild ocular discomfort up to an intolerable pain evoked by innocuous stimuli. In refractory cases, the persistence of this harmful signal is able to evoke a mechanism of maladaptive plasticity of the nervous system that leads to increased pain responsiveness. Peripheral and, subsequently, central sensitization cause nociceptor hyperexcitability and persistent pain perception that can culminate in the paradoxical situation of perceiving eye pain even in the absence of ocular surface abnormalities. Effective therapeutic strategies of these cases are challenging, and new options are desirable. Recently, a theoretical novel therapeutic approach concerns enkephalins thanks to the evidence that eye pain sensations are modulated by endogenous opioid peptides (enkephalins, endorphins and dynorphins). In this regard, new topical agents open up a new theoretical scenario in the treatment of ocular discomfort and eye pain in the setting of DED, such as, for example, a multimolecular complex based on proteins and glycosaminoglycans also containing opiorphin that may assist the physiological pain-relieving mechanism of the eye.
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Tran BN, Maass M, Musial G, Stern ME, Gehlsen U, Steven P. Topical application of cannabinoid-ligands ameliorates experimental dry-eye disease. Ocul Surf 2021; 23:131-139. [PMID: 34922011 DOI: 10.1016/j.jtos.2021.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/30/2021] [Accepted: 12/13/2021] [Indexed: 11/27/2022]
Abstract
PURPOSE Dry eye disease (DED) is a multifactorial disease, with limitations regarding efficacy and tolerability of applied substances. Among several candidates, the endocannabinoid system with its receptors (CB1R and CB2R) were reported to modulate inflammation, wound healing and pain, which are also core DED pathomechanisms. This study is to investigate the therapeutic responses of Δ-9 tetrahydrocannabinol (a non-selective agonist) and two selective antagonists, SR141716A (CB1R antagonist) and SR144528 (CB2R antagonist), as a topical application using a DED mouse model. METHOD Experimental DED was induced in naïve C57BL/6 mice. Expression of CBR at the ocular surface of naïve and DED mice was determined by qPCR and in-situ hybridization. Either THC or CBR antagonists were compounded in an aqueous solution and dosed during the induction of DED. Tear production, cornea sensitivity, and cornea fluorescence staining were tested. At the end of each experiment, corneas were stained with β3-tubulin for analysis of corneal nerve morphology. Conjunctiva was analyzed for CD4+ and CD8+ infiltration. RESULTS CB1R and CB2R are present at the ocular surface, and desiccating stress increased CBR expressions (p < 0.05). After 10 days of DED induction, treated groups demonstrated a reduced CBR expression in the cornea, which was concurrent with improvements in the DED phenotype including fluorescence staining & inflammation. Applying THC protected corneal nerve morphology, thus maintained corneal sensitivity and reduced CD4+ T-cell infiltration. The CB1R antagonist maintained cornea sensitivity without changing nerve morphology. CONCLUSIONS Endocannabinoid receptor modulation presents a potential multi-functional therapeutic approach for DED.
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Affiliation(s)
- Bao N Tran
- Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Martina Maass
- Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Gwen Musial
- Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Michael E Stern
- Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany; ImmunEyez LLC, Irvine, CA, USA
| | - Uta Gehlsen
- Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Philipp Steven
- Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
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Lasagni Vitar RM, Bonelli F, Rama P, Ferrari G. Immunity and pain in the eye: focus on the ocular surface. Clin Exp Immunol 2021; 207:149-163. [PMID: 35020868 PMCID: PMC8982975 DOI: 10.1093/cei/uxab032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/21/2021] [Accepted: 12/10/2021] [Indexed: 02/03/2023] Open
Abstract
Most ocular diseases are associated with pain. While pain has been generally considered a mere (deleterious) additional symptom, it is now emerging that it is a key modulator of innate/adaptive immunity. Because the cornea receives the highest nerve density of the entire body, it is an ideal site to demonstrate interactions between pain and the immune response. Indeed, most neuropeptides involved in pain generation are also potent regulators of innate and adaptive leukocyte physiology. On the other hand, most inflammatory cells can modulate the generation of ocular pain through release of specific mediators (cytokines, chemokines, growth factors, and lipid mediators). This review will discuss the reciprocal role(s) of ocular surface (and specifically: corneal) pain on the immune response of the eye. Finally, we will discuss the clinical implications of such reciprocal interactions in the context of highly prevalent corneal diseases.
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Affiliation(s)
- Romina Mayra Lasagni Vitar
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Filippo Bonelli
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Paolo Rama
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Giulio Ferrari
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy,Correspondence: Giulio Ferrari, Cornea and Ocular Surface Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy. E-mail:
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Lasagni Vitar RM, Rama P, Ferrari G. The two-faced effects of nerves and neuropeptides in corneal diseases. Prog Retin Eye Res 2021; 86:100974. [PMID: 34098111 DOI: 10.1016/j.preteyeres.2021.100974] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 12/16/2022]
Abstract
Corneal nerves are instrumental to maintain cornea integrity through regulation of key physiological functions such as tear secretion, blink reflex, and neuropeptide turnover. Corneal nerve injury/stimulation can follow many insults including mechanical/chemical trauma, infections and surgeries. Nerve disruption initiates a process named neurogenic inflammation which leads to edema, pain, and recruitment and activation of leukocytes. Interestingly, leukocyte influx in the cornea can further damage nerves by releasing inflammatory mediators-including neuropeptides. The clinical outcome of neuroinflammation can be beneficial or detrimental to corneal integrity. On one side, it ensures prompt wound healing and prevents infections. On the other, prolonged and/or deranged neuroinflammation can permanently disrupt corneal integrity and impair vision. The cornea is an ideal site to study peripheral neuroinflammation and neurogenic inflammation since it receives the highest density of sensory nerves of the entire body. We will review the corneal nerve anatomy and neurochemistry, discuss the beneficial and detrimental effects of neurogenic inflammation in corneal wound healing, inflammatory processes, and pain. We will also examine the emerging remote impact of corneal nerve disruption on the trigeminal ganglion and the brain, highlighting the key role of neuropeptide Substance P. Finally, we will discuss the clinical relevance of such neuroinflammatory network in the context of severe and highly prevalent ocular diseases, including potential treatments.
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Affiliation(s)
- Romina Mayra Lasagni Vitar
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Paolo Rama
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Giulio Ferrari
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy.
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Fakih D, Guerrero-Moreno A, Baudouin C, Goazigo AR, Parsadaniantz SM. Capsazepine decreases corneal pain syndrome in severe dry eye disease. J Neuroinflammation 2021; 18:111. [PMID: 33975636 DOI: 10.1186/s12974-021-02162-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/29/2021] [Indexed: 11/26/2022] Open
Abstract
Background Dry eye disease (DED) is a multifactorial disease of the ocular surface accompanied by neurosensory abnormalities. Here, we evaluated the effectiveness of transient receptor potential vanilloid-1 (TRPV1) blockade to alleviate ocular pain, neuroinflammation, and anxiety-like behavior associated with severe DED. Methods Chronic DED was induced by unilateral excision of the Harderian and extraorbital lacrimal glands of adult male mice. Investigations were conducted at 21 days after surgery. The mRNA levels of TRPV1, transient receptor potential ankyrin-1 (TRPA1), and acid-sensing ion channels 1 and 3 (ASIC1 and ASIC3) in the trigeminal ganglion (TG) were evaluated by RNAscope in situ hybridization. Multi-unit extracellular recording of ciliary nerve fiber activity was used to monitor spontaneous and stimulated (cold, heat, and acid) corneal nerve responsiveness in ex vivo eye preparations. DED mice received topical instillations of the TRPV1 antagonist (capsazepine) twice a day for 2 weeks from d7 to d21 after surgery. The expression of genes involved in neuropathic and inflammatory pain was evaluated in the TG using a global genomic approach. Chemical and mechanical corneal nociception and spontaneous ocular pain were monitored. Finally, anxiety-like behaviors were assessed by elevated plus maze and black and white box tests. Results First, in situ hybridization showed DED to trigger upregulation of TRPV1, TRPA1, ASIC1, and ASIC3 mRNA in the ophthalmic branch of the TG. DED also induced overexpression of genes involved in neuropathic and inflammatory pain in the TG. Repeated instillations of capsazepine reduced corneal polymodal responsiveness to heat, cold, and acidic stimulation in ex vivo eye preparations. Consistent with these findings, chronic capsazepine instillation inhibited the upregulation of genes involved in neuropathic and inflammatory pain in the TG of DED animals and reduced the sensation of ocular pain, as well as anxiety-like behaviors associated with severe DED. Conclusion These data provide novel insights on the effectiveness of TRPV1 antagonist instillation in alleviating abnormal corneal neurosensory symptoms induced by severe DED, opening an avenue for the repositioning of this molecule as a potential analgesic treatment for patients suffering from chronic DED.
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