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Yalçın MB, Bora ES, Erdoğan MA, Çakır A, Erbaş O. The Effect of Adipose-Derived Mesenchymal Stem Cells on Peripheral Nerve Damage in a Rodent Model. J Clin Med 2023; 12:6411. [PMID: 37835055 PMCID: PMC10573691 DOI: 10.3390/jcm12196411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/27/2023] [Accepted: 10/07/2023] [Indexed: 10/15/2023] Open
Abstract
Peripheral nerve damage is a significant clinical problem with limited therapeutic options. Adipose-derived mesenchymal stem cells (ADSCs) have emerged as a promising therapeutic approach due to their regenerative potential. However, the underlying mechanisms by which ADSCs promote peripheral nerve regeneration remain unclear. In this study, we investigated the role of syndecan-1 and heat shock protein 70 (HSP-70) in mediating the regenerative effects of ADSCs on peripheral nerves. ADSCs were characterized and isolated from the adipose tissue of rats. In vitro experiments were conducted to evaluate the ability of ADSCs to secrete syndecan-1 and HSP-70 in response to stress conditions. To evaluate the therapeutic potential of ADSCs, rats with sciatic nerve injuries were treated with ADSCs and assessed for functional recovery, nerve regeneration, and changes in syndecan-1 and HSP-70 levels. Regeneration was evaluated with Electromyography (EMG) histology. The results showed that ADSCs could secrete syndecan-1 and HSP-70 in response to stress conditions. Furthermore, ADSC treatment significantly improved functional recovery and nerve regeneration and increased syndecan-1 and HSP-70 levels in the injured nerve. On the other hand, ADSCs make improvements histologically through the influence of Nerve growth factor (NGF), Malondialdehyde (MDA), and EMG.
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Affiliation(s)
- Mehmet Burak Yalçın
- Department of Orthopedics and Traumatology, Bahcelievler Memorial Hospital, Istanbul 34180, Turkey;
| | - Ejder Saylav Bora
- Department of Emergency Medicine, Izmir Atatürk Research and Training Hospital, Izmir 35360, Turkey
| | - Mümin Alper Erdoğan
- Department of Physiology, Faculty of Medicine, Izmir Kâtip Çelebi University, Izmir 35620, Turkey;
| | - Adem Çakır
- Department of Emergency Medicine, Çanakkale Mehmet Akif Ersoy State Hospital, Çanakkale 17100, Turkey;
| | - Oytun Erbaş
- Department of Physiology, Demiroğlu Bilim University, Istanbul 34394, Turkey;
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2
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Segars KL, Trinkaus-Randall V. Glycosaminoglycans: Roles in wound healing, formation of corneal constructs and synthetic corneas. Ocul Surf 2023; 30:85-91. [PMID: 37657650 PMCID: PMC11059988 DOI: 10.1016/j.jtos.2023.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/31/2023] [Accepted: 08/29/2023] [Indexed: 09/03/2023]
Abstract
Maintaining the clarity of the cornea is essential for vision, and is achieved through an exquisite array of collagen fibrils and proteoglycans in the corneal stroma. Alterations in the identity and modifications of the glycosaminoglycans (GAGs) are seen both throughout the normal wound healing process and in pathological conditions resulting in corneal opacity. Understanding these changes has been essential for the development of corneal prostheses and corneal reconstruction. The goal of this review article is to summarize and consolidate research in the alterations seen in glycosaminoglycans in injured and hypoxic states, address the role of proteins that can regulate glycosaminoglycans in the corneal wound healing process, and apply these findings to the context of corneal restoration through reconstruction or the insertion of synthetic devices.
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Affiliation(s)
- Kristen L Segars
- Departments of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, 02118, USA
| | - Vickery Trinkaus-Randall
- Department of Biochemistry and Cell Biology, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, 02118, USA; Department of Ophthalmology, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, 02118, USA.
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3
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Recovery of Corneal Innervation after Treatment in Dry Eye Disease: A Confocal Microscopy Study. J Clin Med 2023; 12:jcm12051841. [PMID: 36902628 PMCID: PMC10003258 DOI: 10.3390/jcm12051841] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/23/2023] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
PURPOSE To analyze the changes in corneal innervation by means of in vivo corneal confocal microscopy (IVCM) in patients diagnosed with Evaporative (EDE) and Aqueous Deficient Dry Eye (ADDE) and treated with a standard treatment for Dry Eye Disease (DED) in combination with Plasma Rich in Growth Factors (PRGF). METHODS Eighty-three patients diagnosed with DED were enrolled in this study and included in the EDE or ADDE subtype. The primary variables analyzed were the length, density and number of nerve branches, and the secondary variables were those related to the quantity and stability of the tear film and the subjective response of the patients measured with psychometric questionnaires. RESULTS The combined treatment therapy with PRGF outperforms the standard treatment therapy in terms of subbasal nerve plexus regeneration, significantly increasing length, number of branches and nerve density, as well as significantly improving the stability of the tear film (p < 0.05 for all of them), and the most significant changes were located in the ADDE subtype. CONCLUSIONS the corneal reinnervation process responds in a different way depending on the treatment prescribed and the subtype of dry eye disease. In vivo confocal microscopy is presented as a powerful technique in the diagnosis and management of neurosensory abnormalities in DED.
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Schwend T. Wiring the ocular surface: A focus on the comparative anatomy and molecular regulation of sensory innervation of the cornea. Differentiation 2023:S0301-4681(23)00010-5. [PMID: 36997455 DOI: 10.1016/j.diff.2023.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/23/2023] [Indexed: 01/29/2023]
Abstract
The cornea is richly innervated with sensory nerves that function to detect and clear harmful debris from the surface of the eye, promote growth and survival of the corneal epithelium and hasten wound healing following ocular disease or trauma. Given their importance to eye health, the neuroanatomy of the cornea has for many years been a source of intense investigation. Resultantly, complete nerve architecture maps exist for adult human and many animal models and these maps reveal few major differences across species. Interestingly, recent work has revealed considerable variation across species in how sensory nerves are acquired during developmental innervation of the cornea. Highlighting such species-distinct key differences, but also similarities, this review provides a full, comparative anatomy analysis of sensory innervation of the cornea for all species studied to date. Further, this article comprehensively describes the molecules that have been shown to guide and direct nerves toward, into and through developing corneal tissue as the final architectural pattern of the cornea's neuroanatomy is established. Such knowledge is useful for researchers and clinicians seeking to better understand the anatomical and molecular basis of corneal nerve pathologies and to hasten neuro-regeneration following infection, trauma or surgery that damage the ocular surface and its corneal nerves.
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Efraim Y, Chen FYT, Cheong KN, Gaylord EA, McNamara NA, Knox SM. A synthetic tear protein resolves dry eye through promoting corneal nerve regeneration. Cell Rep 2022; 40:111307. [PMID: 36044852 PMCID: PMC9549932 DOI: 10.1016/j.celrep.2022.111307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/17/2022] [Accepted: 08/11/2022] [Indexed: 11/27/2022] Open
Abstract
Corneal architecture is essential for vision and is greatly perturbed by the absence of tears due to the highly prevalent disorder dry eye. With no regenerative therapies available, pathological alterations of the ocular surface in response to dryness, including persistent epithelial defects and poor wound healing, result in life-long morbidity. Here, using a mouse model of aqueous-deficient dry eye, we reveal that topical application of the synthetic tear protein Lacripep reverses the pathological outcomes of dry eye through restoring the extensive network of corneal nerves that are essential for tear secretion, barrier function, epithelial homeostasis, and wound healing. Intriguingly, the restorative effects of Lacripep occur despite extensive immune cell infiltration, suggesting tissue reinnervation and regeneration can be achieved under chronic inflammatory conditions. In summary, our data highlight Lacripep as a first-in-class regenerative therapy for returning the cornea to a near homeostatic state in individuals who suffer from dry eye. Currently, there are no regenerative treatments for ocular pathologies due to dry eye. Efraim et al. demonstrate the synthetic tear peptide Lacripep as a regenerative therapy capable of restoring the damaged, dysfunctional ocular surface to a near homeostatic state through promoting nerve regeneration in the presence of chronic inflammation.
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Affiliation(s)
- Yael Efraim
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Feeling Yu Ting Chen
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ka Neng Cheong
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Eliza A Gaylord
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Nancy A McNamara
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Oakland, CA 94720, USA; Department of Anatomy, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Sarah M Knox
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA.
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Vang S, Cochran P, Sebastian Domingo J, Krick S, Barnes JW. The Glycobiology of Pulmonary Arterial Hypertension. Metabolites 2022; 12:metabo12040316. [PMID: 35448503 PMCID: PMC9026683 DOI: 10.3390/metabo12040316] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/23/2022] [Accepted: 03/28/2022] [Indexed: 01/27/2023] Open
Abstract
Pulmonary arterial hypertension (PAH) is a progressive pulmonary vascular disease of complex etiology. Cases of PAH that do not receive therapy after diagnosis have a low survival rate. Multiple reports have shown that idiopathic PAH, or IPAH, is associated with metabolic dysregulation including altered bioavailability of nitric oxide (NO) and dysregulated glucose metabolism. Multiple processes such as increased proliferation of pulmonary vascular cells, angiogenesis, apoptotic resistance, and vasoconstriction may be regulated by the metabolic changes demonstrated in PAH. Recent reports have underscored similarities between metabolic abnormalities in cancer and IPAH. In particular, increased glucose uptake and altered glucose utilization have been documented and have been linked to the aforementioned processes. We were the first to report a link between altered glucose metabolism and changes in glycosylation. Subsequent reports have highlighted similar findings, including a potential role for altered metabolism and aberrant glycosylation in IPAH pathogenesis. This review will detail research findings that demonstrate metabolic dysregulation in PAH with an emphasis on glycobiology. Furthermore, this report will illustrate the similarities in the pathobiology of PAH and cancer and highlight the novel findings that researchers have explored in the field.
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Abstract
Laser scanning in vivo confocal microscopy is a useful clinical tool to assess the corneal nerves in human and laboratory animals. With this new technology, the use of terms such as “neuromas” and “microneuromas” is becoming popular to describe nerve structures seen in humans. Here, we point out that the sites where stromal nerves enter the corneal epithelium are often hyperreflective and can appear dysmorphic when imaged using in vivo confocal microscopy. Furthermore, we clarify what is known anatomically about how the nerves enter the corneal epithelium from the stroma, and we urge colleagues to differentiate between hyperreflective foci at the corneal stromal–epithelial nerve penetration sites and alterations in nerve morphology secondary to injury or disease.
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Bargagna‐Mohan P, Schultz G, Rheaume B, Trakhtenberg EF, Robson P, Pal‐Ghosh S, Stepp MA, Given KS, Macklin WB, Mohan R. Corneal nonmyelinating Schwann cells illuminated by single-cell transcriptomics and visualized by protein biomarkers. J Neurosci Res 2021; 99:731-749. [PMID: 33197966 PMCID: PMC7894186 DOI: 10.1002/jnr.24757] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 10/05/2020] [Accepted: 10/25/2020] [Indexed: 12/23/2022]
Abstract
The cornea is the most innervated tissue in the human body. Myelinated axons upon inserting into the peripheral corneal stroma lose their myelin sheaths and continue into the central cornea wrapped by only nonmyelinating corneal Schwann cells (nm-cSCs). This anatomical organization is believed to be important for central vision. Here we employed single-cell RNA sequencing (scRNA-seq), microscopy, and transgenics to characterize these nm-cSCs of the central cornea. Using principal component analysis, uniform manifold approximation and projection, and unsupervised hierarchal cell clustering of scRNA-seq data derived from central corneal cells of male rabbits, we successfully identified several clusters representing different corneal cell types, including a unique cell cluster representing nm-cSCs. To confirm protein expression of cSC genes, we performed cross-species validation, employing corneal whole-mount immunostaining with confocal microscopy in mouse corneas. The expression of several representative proteins of nm-cSCs were validated. As the proteolipid protein 1 (PLP1) gene was also expressed in nm-cSCs, we explored the Plp1-eGFP transgenic reporter mouse line to visualize cSCs. Specific and efficient eGFP expression was observed in cSCs in adult mice of different ages. Of several putative cornea-specific SC genes identified, Dickkopf-related protein 1 was shown to be present in nm-cSCs. Taken together, our findings, for the first time, identify important insights and tools toward the study nm-cSCs in isolated tissue and adult animals. We expect that our results will advance the future study of nm-cSCs in applications of nerve repair, and provide a resource for the study of corneal sensory function.
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Affiliation(s)
- Paola Bargagna‐Mohan
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
| | - Gwendolyn Schultz
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
| | - Bruce Rheaume
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
| | | | - Paul Robson
- Department of Genetics & Genome SciencesUniversity of Connecticut Health CenterFarmingtonCTUSA
- The Jackson Laboratory for Genomic MedicineFarmingtonCTUSA
| | - Sonali Pal‐Ghosh
- Department of Anatomy and Regenerative BiologyGeorge Washington University Medical SchoolWashingtonDCUSA
| | - Mary Ann Stepp
- Department of Anatomy and Regenerative BiologyGeorge Washington University Medical SchoolWashingtonDCUSA
| | - Katherine S. Given
- Department of Cell and Developmental BiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Wendy B. Macklin
- Department of Cell and Developmental BiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Royce Mohan
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
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Tadvalkar G, Pal-Ghosh S, Pajoohesh-Ganji A, Stepp MA. The impact of euthanasia and enucleation on mouse corneal epithelial axon density and nerve terminal morphology. Ocul Surf 2020; 18:821-828. [PMID: 32798735 DOI: 10.1016/j.jtos.2020.07.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Here we study the impact of using either CO2 gas or cervical dislocation (CD) for euthanasia and using different techniques to enucleate the eye on preserving axonal density and morphology of the intraepithelial corneal nerves (ICNs). OBJECTIVES To determine whether using CO2 gas or CD for euthanasia and enucleating by cutting or pulling eyes out impacts axon density and nerve terminal morphology in the mouse cornea. METHODS Mice were euthanized by CO2 gas or CD; the impact of delaying fixation for 5 min post-euthanasia was also assessed. We tested two different techniques to enucleate the eyes: cutting the optic nerve by curved scissors or pulling the eye out. A minimum of 10 corneas from 5 male and female BALB/c mice were used for each variable. Axons and intraepithelial corneal nerve terminals (ICNTs) were visualized utilizing βIII tubulin and L1CAM and quantified using confocal microscopy. RESULTS The variations seen in axon density between individual mice are not gender- or euthanasia-dependent. A significant reduction in axon density and loss of ICNT morphology are observed in eyes enucleated by pulling the optic nerve out. Similar results are obtained in male and female mice. CONCLUSION While the variations tested in euthanasia do not affect axon density in male and female mouse corneas, enucleation by proptosing and gently cutting out the eyes yields increased axon density and improved ICNT morphology compared to pulling eyes out and leaving the optic nerve attached.
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Affiliation(s)
- Gauri Tadvalkar
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA
| | - Sonali Pal-Ghosh
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA
| | - Ahdeah Pajoohesh-Ganji
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA
| | - Mary Ann Stepp
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA; Department of Ophthalmology, The George Washington School of Medicine and Health Sciences, Washington DC, 20037, USA.
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10
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Puri S, Coulson-Thomas YM, Gesteira TF, Coulson-Thomas VJ. Distribution and Function of Glycosaminoglycans and Proteoglycans in the Development, Homeostasis and Pathology of the Ocular Surface. Front Cell Dev Biol 2020; 8:731. [PMID: 32903857 PMCID: PMC7438910 DOI: 10.3389/fcell.2020.00731] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/15/2020] [Indexed: 12/20/2022] Open
Abstract
The ocular surface, which forms the interface between the eye and the external environment, includes the cornea, corneoscleral limbus, the conjunctiva and the accessory glands that produce the tear film. Glycosaminoglycans (GAGs) and proteoglycans (PGs) have been shown to play important roles in the development, hemostasis and pathology of the ocular surface. Herein we review the current literature related to the distribution and function of GAGs and PGs within the ocular surface, with focus on the cornea. The unique organization of ECM components within the cornea is essential for the maintenance of corneal transparency and function. Many studies have described the importance of GAGs within the epithelial and stromal compartment, while very few studies have analyzed the ECM of the endothelial layer. Importantly, GAGs have been shown to be essential for maintaining corneal homeostasis, epithelial cell differentiation and wound healing, and, more recently, a role has been suggested for the ECM in regulating limbal stem cells, corneal innervation, corneal inflammation, corneal angiogenesis and lymphangiogenesis. Reports have also associated genetic defects of the ECM to corneal pathologies. Thus, we also highlight the role of different GAGs and PGs in ocular surface homeostasis, as well as in pathology.
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Affiliation(s)
- Sudan Puri
- College of Optometry, University of Houston, Houston, TX, United States
| | - Yvette M Coulson-Thomas
- Molecular Biology Section, Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tarsis F Gesteira
- College of Optometry, University of Houston, Houston, TX, United States.,Optimvia, LLC, Batavia, OH, United States
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11
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Seyed-Safi AG, Daniels JT. A validated porcine corneal organ culture model to study the limbal response to corneal epithelial injury. Exp Eye Res 2020; 197:108063. [PMID: 32417262 DOI: 10.1016/j.exer.2020.108063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/03/2020] [Accepted: 05/05/2020] [Indexed: 12/13/2022]
Abstract
Limbal epithelial stem cells are required for the maintenance and repair of the corneal epithelial surface. The difficulty in obtaining human corneal tissue for research purposes means that animal models for studying the corneal and limbal epithelium are extremely useful. Porcine corneal tissue represents an attractive experimental model, however, functional analysis of the limbal epithelial cell population is needed to validate the use of this tissue. Single cell clonal analysis revealed that holoclone-generating cells were enriched in the limbus as compared with the central cornea (38.3% vs 8.3%) and that label-retaining cells were also enriched in the limbus and compared with the central cornea (44.7 ± 6.4 vs 4.7 ± 1.5). Furthermore, it was demonstrated that in a 3D-printed organ culture system, porcine tissue was capable of maintaining and healing the corneal epithelium. Ki67 staining of corneal sections revealed that in response to central epithelial wounding, a greater proportion of progenitors in the basal limbal epithelium enter an actively dividing state. The authors present a comprehensively validated model system for studying the interactions between limbal niche factors and limbal epithelial stem cell fate.
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12
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Parlanti P, Pal-Ghosh S, Williams A, Tadvalkar G, Popratiloff A, Stepp MA. Axonal debris accumulates in corneal epithelial cells after intraepithelial corneal nerves are damaged: A focused Ion Beam Scanning Electron Microscopy (FIB-SEM) study. Exp Eye Res 2020; 194:107998. [PMID: 32209319 PMCID: PMC7697722 DOI: 10.1016/j.exer.2020.107998] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/13/2020] [Accepted: 03/07/2020] [Indexed: 12/15/2022]
Abstract
The intraepithelial corneal nerves (ICNs) that innervate the corneal epithelium are maintained through interactions with corneal epithelial cells and the extracellular matrix they produce. One to several axons bundle together within the basal cell layer and extend parallel to the ocular surface or branch and extend apically. Here we use 3-dimentional (3D) ultrastructural reconstructions of control and trephine injured mouse corneal epithelium and stroma produced using Focused Ion Beam Scanning Electron Microscope (FIB-SEM) to determine whether corneal epithelial or immune cells resident in the epithelium remove axonal debris and degrade it in their lysosomes after trephine injury to the cornea. We demonstrate that axonal fragments are internalized in the corneal epithelium and accumulate within electron dense structures consistent with lysosomes 3 h after trephine injury in both epithelial and immune cells located among the basal cells of the trephine injured cornea. Confocal imaging showed fewer CD45+ immune cells within the corneal epithelium after trephine injury compared to controls. The resolution obtained using FIB-SEM also allowed us to show that the presence of sensory axons at the basal aspect of the epithelial basal cells close to the anterior aspect of the epithelial basement membrane (EBM) is associated with a focal reduction in EBM thickness. In addition, we show using FIB-SEM and confocal imaging that superficial trephine injuries that do not penetrate the stroma, damage the integrity of anterior stromal nerves. These studies are the first to look at the mouse cornea following nerve injury using FIB-SEM.
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Affiliation(s)
- Paola Parlanti
- GW Nanofabrication and Imaging Center, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA
| | - Sonali Pal-Ghosh
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA
| | - Alexa Williams
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA
| | - Gauri Tadvalkar
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA
| | - Anastas Popratiloff
- GW Nanofabrication and Imaging Center, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA; Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA
| | - Mary Ann Stepp
- Department of Anatomy and Cell Biology, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA; Department of Ophthalmology, The George Washington School of Medicine and Health Sciences, Washington DC, 20052, USA.
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13
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Patel M, Pham NTK, Ziegenhorn E, Pisano A, Deaton RJ, Kim S, Rajarathnam V, Schwend T. Unique and overlapping effects of triiodothyronine (T3) and thyroxine (T4) on sensory innervation of the chick cornea. Exp Eye Res 2020; 194:108007. [PMID: 32194064 DOI: 10.1016/j.exer.2020.108007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 02/01/2020] [Accepted: 03/15/2020] [Indexed: 12/28/2022]
Abstract
Multiple aspects of cornea development, including the innervation of the cornea by trigeminal axons, are sensitive to embryonic levels of thyroid hormone (TH). Although previous work showed that increased TH levels could enhance the rate of axonal extension within the cornea in a thyroxine (T4)-dependent manner, details underlying the stimulatory effect of TH on cornea innervation are unclear. Here, by examining the effects throughout all stages of cornea innervation of the two main THs, triiodothyronine (T3) and T4, we provide a more complete characterization of the stimulatory effects of TH on corneal nerves and begin to unravel the underlying molecular mechanisms. During development, trigeminal axons are initially repelled at the corneal periphery and encircle the cornea in a pericorneal nerve ring prior to advancing into the corneal stroma radially from all along the nerve ring. Overall, exogenous T3 led to pleiotropic effects throughout all stages of cornea innervation, whereas the effects of exogenous T4 was confined to timepoints following completion of the nerve ring. Specifically, exogenous T3 accelerated the formation of the pericorneal nerve ring. By utilizing in vitro neuronal explants studies we demonstrated that T3 acts as a trophic factor to directly stimulate trigeminal nerve growth. Further, exogenous T3 caused disorganized and precocious innervation of the cornea, accompanied by the downregulation of inhibitory Robo receptors that normally act to regulate the timing of nerve advancement into the Slit-expressing corneal tissues. Following nerve ring completion, the growth rate and branching behavior of nerves as they advanced into and through the cornea were found to be stimulated equally by T3 or T4. These stimulatory influences of T3/T4 over nerves likely arose as secondary consequences brought on by TH-mediated modulations to the corneal extracellular matrix. Specifically, we found that the levels of nerve-inhibitory keratan- and chondroitin-sulfate containing proteoglycans and associated sulfation enzymes were dramatically altered in the presence of exogenous T3 or T4. Altogether, these findings uncover new roles for TH on corneal development and shed insight into the mechanistic basis of both T3 and T4 on cornea innervation.
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Affiliation(s)
- Mansi Patel
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - Ngan T K Pham
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - Elise Ziegenhorn
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - Alyssa Pisano
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | - Ryan J Deaton
- Department of Pathology, University of Illinois at Chicago, Chicago, IL, USA
| | - Shinho Kim
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
| | | | - Tyler Schwend
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA.
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14
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Zhang Y, Liang Q, Zhang Y, Hong L, Lei D, Zhang L. Olmesartan alleviates bleomycin-mediated vascular smooth muscle cell senescence via the miR-665/SDC1 axis. Am J Transl Res 2020; 12:5205-5220. [PMID: 33042414 PMCID: PMC7540088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 08/01/2020] [Indexed: 12/08/2022]
Abstract
Olmesartan (OMST) is a new angiotensin II receptor antagonist recently approved by the FDA to treat cardiovascular diseases. We investigated the molecular mechanisms by which OMST regulates vascular senescence. In the present study, bleomycin (BLM) was used to induce senescence in vascular smooth muscle cells (VSMCs); after which, the cells were treated with OMST. The effects of OMST on BLM-mediated cell senescence were evaluated using cell adhesion, NAD+/NADH, and Annevin V/PI double staining assays, as well as by immunofluorescence staining of γH2AX, Edu flow cytometry, and evaluations of senescence-associated β-gal activity. Differentially expressed microRNAs (DEMs) were identified by miRNA microarray assays, and subsequently validated by quantitative real time PCR. Bisulfite sequencing PCR (BSP) was used to detect the methylation status of the miR-665 promoter. The target genes of miR-665 were predicted and confirmed using luciferase reporter assays. We found that miR-665 was upregulated in VSMCs in response to BLM-induced cellular senescence. BSP studies revealed that CpG sites in the promoter region of the miR-665 gene underwent extensive demethylation during BLM-induced cellular senescence, and there was a concomitant up-regulation of miR-665 expression. SDC1 mRNA was identified as a direct target of miR-665. Either miR-665 overexpression or SDC1 knockdown significantly reversed the effects of OMST on BLM-induced VSMC senescence. Moreover, SDC1 overexpression partially reversed the changes that occurred in cells with BLM-induced senescence caused by miR-665 overexpression. Our findings suggest that the miR-665/SDC1 axis functions as a vital modulator of VSMC senescence, and may represent a novel biological target for treating atherosclerosis.
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Affiliation(s)
- Yi Zhang
- Department of Cardiology, The First Affiliated Hospital of Guangdong Pharmaceutical University Guangzhou 510080, Guangdong, China
| | - Qingyang Liang
- Department of Cardiology, The First Affiliated Hospital of Guangdong Pharmaceutical University Guangzhou 510080, Guangdong, China
| | - Yanan Zhang
- College of Veterinary Medicine, Northeast Agricultural University Harbin 150030, China
| | - Lei Hong
- Department of Cardiology, Long Gang Central Hospital of Shenzhen Shenzhen 518116, Guangdong, China
| | - Da Lei
- Department of Cardiology, The First Affiliated Hospital of Guangdong Pharmaceutical University Guangzhou 510080, Guangdong, China
| | - Li Zhang
- Department of Cardiology, The First Affiliated Hospital of Guangdong Pharmaceutical University Guangzhou 510080, Guangdong, China
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15
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Abstract
The cornea is a transparent outermost structure of the eye anterior segment comprising the highest density of innervated tissue. In the process of corneal innervation, trigeminal ganglion originated corneal nerves diligently traverse different corneal cell types in different corneal layers including the corneal stroma and epithelium. While crossing the stromal and epithelial cell layers during innervation, due to the existing physical contacts, close interactions occur between stromal keratocytes, epithelial cells, resident immune cells and corneal nerves. Furthermore, by producing various trophic and growth factors corneal cells assist in maintaining the growth and function of corneal nerves. Similarly, corneal nerve generated growth factors critically modify the corneal cell function in all the corneal layers. Due to their close association and contacts, on-going cross-communication between these cell types and corneal nerves play a vital role in the modulation of corneal nerve function, regeneration during wound healing. The present review highlights the influence of different corneal cell types and growth factors released from these cells on corneal nerve regeneration and function.
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Affiliation(s)
- Bhavani S Kowtharapu
- Department of Ophthalmology, Rostock University Medical Centre, Rostock, Germany
| | - Oliver Stachs
- Department of Ophthalmology, Rostock University Medical Centre, Rostock, Germany
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16
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McKay TB, Seyed-Razavi Y, Ghezzi CE, Dieckmann G, Nieland TJF, Cairns DM, Pollard RE, Hamrah P, Kaplan DL. Corneal pain and experimental model development. Prog Retin Eye Res 2019; 71:88-113. [PMID: 30453079 PMCID: PMC6690397 DOI: 10.1016/j.preteyeres.2018.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 11/03/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022]
Abstract
The cornea is a valuable tissue for studying peripheral sensory nerve structure and regeneration due to its avascularity, transparency, and dense innervation. Somatosensory innervation of the cornea serves to identify changes in environmental stimuli at the ocular surface, thereby promoting barrier function to protect the eye against injury or infection. Due to regulatory demands to screen ocular safety of potential chemical exposure, a need remains to develop functional human tissue models to predict ocular damage and pain using in vitro-based systems to increase throughput and minimize animal use. In this review, we summarize the anatomical and functional roles of corneal innervation in propagation of sensory input, corneal neuropathies associated with pain, and the status of current in vivo and in vitro models. Emphasis is placed on tissue engineering approaches to study the human corneal pain response in vitro with integration of proper cell types, controlled microenvironment, and high-throughput readouts to predict pain induction. Further developments in this field will aid in defining molecular signatures to distinguish acute and chronic pain triggers based on the immune response and epithelial, stromal, and neuronal interactions that occur at the ocular surface that lead to functional outcomes in the brain depending on severity and persistence of the stimulus.
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Affiliation(s)
- Tina B McKay
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Yashar Seyed-Razavi
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Chiara E Ghezzi
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Gabriela Dieckmann
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Thomas J F Nieland
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Dana M Cairns
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Rachel E Pollard
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA
| | - Pedram Hamrah
- Center for Translational Ocular Immunology and Cornea Service, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA.
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17
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He M, Han T, Wang Y, Wu YH, Qin WS, Du LZ, Zhao CQ. Effects of HGF and KGF gene silencing on vascular endothelial growth factor and its receptors in rat ultraviolet radiation‑induced corneal neovascularization. Int J Mol Med 2019; 43:1888-1899. [PMID: 30816491 DOI: 10.3892/ijmm.2019.4114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 01/22/2019] [Indexed: 11/05/2022] Open
Abstract
Hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF), two paracrine growth factors, modulate corneal epithelial cell metabolism, apoptosis and survival. Vascular endothelial growth factor (VEGF) serves as a proangiogenic factor in corneal neovascularization (CNV), which is a major cause of vision impairment and corneal blindness. The aim of the present study was to evaluate the ability of HGF and KGF to influence VEGF and its receptor, kinase insert domain receptor (Flk‑1) in corneal injury and CNV in rats induced by ultraviolet radiation (UVR). An UVR‑induced corneal injury rat model was successfully established to characterize the expression patterns of KGF, HGF, VEGF and Flk‑1 in corneal tissues. Corneal epithelial cells were extracted and treated with small interfering RNAs (siRNAs) targeting KGF, HGF or both (si‑KGF, si‑HGF or si‑HGF/KGF). The effects of HGF and KGF were examined through detection of the expression of KGF, HGF, VEGF and Flk‑1, and the evaluation of cell proliferation, cell cycle and cell apoptosis. The expression levels of KGF, HGF, VEGF and Flk‑1 in corneal tissues were increased in the rat model. In the cell experiments, the transfection of si‑HGF/KGF resulted in reductions in VEGF, Flk‑1, KGF and HGF. In addition, decreased cell proliferation and elevated cell apoptosis were found in the corneal epithelial cells from the rat model following KGF and HGF gene silencing. Taken together, these findings suggest that HGF and KGF gene silencing inhibits UVR‑induced corneal epithelial proliferation and CNV and may function as novel targets for corneal wound healing.
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Affiliation(s)
- Min He
- Department of Ophthalmology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Tao Han
- Clinical Medical College, Second Military Medical University, Shanghai 200433, P.R. China
| | - Yan Wang
- Bayi Children's Hospital Affiliated to PLA Army General Hospital, Beijing 100700, P.R. China
| | - Yao-Hong Wu
- Department of Ophthalmology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Wei-Shan Qin
- Department of Ophthalmology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Ling-Zhen Du
- Department of Ophthalmology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Chang-Qing Zhao
- Department of Otolaryngology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
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18
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Stepp MA, Pal-Ghosh S, Tadvalkar G, Williams AR, Pflugfelder SC, de Paiva CS. Reduced Corneal Innervation in the CD25 Null Model of Sjögren Syndrome. Int J Mol Sci 2018; 19:ijms19123821. [PMID: 30513621 PMCID: PMC6320862 DOI: 10.3390/ijms19123821] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 12/20/2022] Open
Abstract
Decreased corneal innervation is frequent in patients with Sjögren Syndrome (SS). To investigate the density and morphology of the intraepithelial corneal nerves (ICNs), corneal sensitivity, epithelial cell proliferation, and changes in mRNA expression of genes that are involved in autophagy and axon targeting and extension were assessed using the IL-2 receptor alpha chain (CD25 null) model of SS. ICN density and thickness in male and female wt and CD25 null corneas were assessed at 4, 6, 8, and 10/11 wk of age. Cell proliferation was assessed using ki67. Mechanical corneal sensitivity was measured. Quantitative PCR was performed to quantify expression of beclin 1, LC3, Lamp-1, Lamp-2, CXCL-1, BDNF, NTN1, DCC, Unc5b1, Efna4, Efna5, Rgma, and p21 in corneal epithelial mRNA. A significant reduction in corneal axon density and mechanical sensitivity were observed, which negatively correlate with epithelial cell proliferation. CD25 null mice have increased expression of genes regulating autophagy (beclin-1, LC3, LAMP-1, LAMP-2, CXCL1, and BDNF) and no change was observed in genes that were related to axonal targeting and extension. Decreased anatomic corneal innervation in the CD25 null SS model is accompanied by reduced corneal sensitivity, increased corneal epithelial cell proliferation, and increased expression of genes regulating phagocytosis and autophagy.
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Affiliation(s)
- Mary Ann Stepp
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
- Department of Ophthalmology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
| | - Sonali Pal-Ghosh
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
| | - Gauri Tadvalkar
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
| | - Alexa R Williams
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
| | - Stephen C Pflugfelder
- Department of Ophthalmology, Ocular Surface Center, Cullen Eye Institute, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Cintia S de Paiva
- Department of Ophthalmology, Ocular Surface Center, Cullen Eye Institute, Baylor College of Medicine, Houston, TX 77030, USA.
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19
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Molecular basis of Mitomycin C enhanced corneal sensory nerve repair after debridement wounding. Sci Rep 2018; 8:16960. [PMID: 30446696 PMCID: PMC6240058 DOI: 10.1038/s41598-018-35090-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 10/25/2018] [Indexed: 12/30/2022] Open
Abstract
The ocular surface is covered by stratified squamous corneal epithelial cells that are in cell:cell contact with the axonal membranes of a dense collection of sensory nerve fibers that act as sentinels to detect chemical and mechanical injuries which could lead to blindness. The sheerness of the cornea makes it susceptible to superficial abrasions and recurrent erosions which demand continuous regrowth of the axons throughout life. We showed previously that topical application of the antibiotic and anticancer drug Mitomycin C (MMC) enhances reinnervation of the corneal nerves and reduces recurrent erosions in mice via an unknown mechanism. Here we show using RNA-seq and confocal imaging that wounding the corneal epithelium by debridement upregulates proteases and protease inhibitors within the epithelium and leads to stromal nerve disruption. MMC attenuates these effects after debridement injury by increasing serpine1 gene and protein expression preserving L1CAM on axon surfaces of reinnervating sensory nerves. These data demonstrate at the molecular level that gene expression changes in the corneal epithelium and stroma modulate sensory axon integrity. By preserving the ability of axons to adhere to corneal epithelial cells, MMC enhances sensory nerve recovery after mechanical debridement injury.
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20
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de Paiva CS. Highlights from the 21st International Ocular Surface Society meeting. Ocul Surf 2018; 16:394-397. [PMID: 30130576 DOI: 10.1016/j.jtos.2018.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/06/2018] [Accepted: 08/14/2018] [Indexed: 11/19/2022]
Affiliation(s)
- Cintia S de Paiva
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA.
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21
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Talbot CJ, Kubilus JK. Developmental analysis of SV2 in the embryonic chicken corneal epithelium. Exp Eye Res 2018; 172:137-143. [PMID: 29654771 DOI: 10.1016/j.exer.2018.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/21/2018] [Accepted: 04/06/2018] [Indexed: 11/20/2022]
Abstract
Intraepithelial corneal nerves (ICNs) help protect the cornea as part of the blink reflex and by modulating tear production. ICNs are also thought to regulate the health and homeostasis of the cornea through the release of trophic factors. Disruption to these nerves can lead to vision loss. Despite their importance little is known about how corneal nerves function and even less is known about how the cornea is initially innervated during its embryonic development. Here, we investigated the innervation of the embryonic chicken cornea. Western blot and immunohistochemistry were used to characterize the localization of the synaptic vesicle marker SV2, a molecule thought to be involved in the release of trophic factors from sensory nerves. The data show that both SV2 and synaptotagmin co-localize to ICNs. Nerves in the conjunctiva also contained SV2 and synaptotagmin, but these were localized to below the basal layers of the conjunctiva epithelium. SV2 isolated from corneal epithelium migrates in western blot at a heavier weight than SV2 isolated from brain, which suggests a role in vesicle targeting, as the deglycosylating enzyme PnGase does not affect corneal SV2.
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Affiliation(s)
- Christopher J Talbot
- Department of Immunology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - James K Kubilus
- Department of Immunology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
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22
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Abstract
Glycosylation is a major form of enzymatic modification of organic molecules responsible for multiple biological processes in an organism. The biosynthesis of glycans is controlled by a series of glycosyltransferases, glycosidases and glycan-modifying enzymes that collectively assemble and process monosaccharide moieties into a diverse array of structures. Many studies have provided insight into various pathways of glycosylation at the ocular surface, such as those related to the biosynthesis of mucin-type O-glycans and N-glycans on proteins, but many others still remain largely unknown. This review provides an overview of the different classes of glycans described at the ocular surface focusing on their biosynthetic pathways and biological relevance. A precise understanding of these pathways under physiological and pathological conditions could help identify biomarkers and novel targets for therapeutic intervention.
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23
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Stepp MA, Pal-Ghosh S, Tadvalkar G, Williams A, Pflugfelder SC, de Paiva CS. Reduced intraepithelial corneal nerve density and sensitivity accompany desiccating stress and aging in C57BL/6 mice. Exp Eye Res 2018; 169:91-98. [PMID: 29407221 PMCID: PMC5949876 DOI: 10.1016/j.exer.2018.01.024] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/25/2018] [Accepted: 01/29/2018] [Indexed: 12/11/2022]
Abstract
Dry Eye disease causes discomfort and pain in millions of patients. Using a mouse acute desiccating stress (DS) model we show that DS induces a reduction in intraepithelial corneal nerve (ICN) density, corneal sensitivity, and apical extension of the intraepithelial nerve terminals (INTs) that branch from the subbasal nerves (SBNs). Topical application of 0.02% Mitomycin C (MMC) or vehicle alone has no impact on the overall loss of axon density due to acute DS. Chronic dry eye, which develops progressively as C57BL/6 mice age, is accompanied by significant loss of the ICNs and corneal sensitivity between 2 and 24 months of age. QPCR studies show that mRNAs for several proteins that regulate axon growth and extension are reduced in corneal epithelial cells by 24 months of age but those that regulate phagocytosis and autophagy are not altered. Taken together, these data demonstrate that dry eye disease is accompanied by alterations in intraepithelial sensory nerve morphology and function and by reduced expression in corneal epithelial cells of mRNAs encoding genes mediating axon extension. Précis: Acute and chronic mouse models of dry eye disease are used to evaluate the pathologic effects of dry eye on the intraepithelial corneal nerves (ICNs) and corneal epithelial cells. Data show reduced numbers of sensory nerves and alterations in nerve morphology, sensitivity, corneal epithelial cell proliferation, and expression of mRNAs for proteins mediating axon extension accompany the pathology induced by dry eye.
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Affiliation(s)
- Mary Ann Stepp
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, USA; Department of Ophthalmology, The George Washington University School of Medicine and Health Sciences, Washington DC, USA.
| | - Sonali Pal-Ghosh
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
| | - Gauri Tadvalkar
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
| | - Alexa Williams
- Department of Anatomy and Regenerative Biology, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
| | - Stephen C Pflugfelder
- Department of Ophthalmology, Ocular Surface Center, Cullen Eye Institute, Baylor College of Medicine, Houston, TX, USA
| | - Cintia S de Paiva
- Department of Ophthalmology, Ocular Surface Center, Cullen Eye Institute, Baylor College of Medicine, Houston, TX, USA
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