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Yang Y, Wang J, Shi Y, Cao H, Wei L, Gao L, Liu M. Oxidation enhances the toxicity of polyethylene microplastics to mouse eye: Perspective from in vitro and in vivo. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 360:124633. [PMID: 39074689 DOI: 10.1016/j.envpol.2024.124633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2024] [Revised: 07/24/2024] [Accepted: 07/27/2024] [Indexed: 07/31/2024]
Abstract
Microplastics (MPs) are ubiquitously dispersed in the environment, and undergoing the process of oxidation that alters their physical and chemical properties. Eyes, which directly interface with the external milieu, inevitably encounter MPs. Nonetheless, the ophthalmic toxicity of MPs towards organisms remains unclear. In this study, primary mouse corneal epithelial cells (MCECs), C57BL/6 mice, and CX3CrlGFP/+ mice were utilized to evaluate the toxicity and differences between oxidized low-density polyethylene MPs (modified-MPs) and low-density polyethylene MPs (virgin-MPs) on eyes. The results manifested that virgin-MPs and modified-MPs could be endocytosed by primary MCECs, resulting in a range of cellular damage. Furthermore, they could diminish tear secretion, increase intraocular pressure, and could be internalized into cornea and retina in mice, instigating a series of detrimental reactions. Importantly, modified-MPs exhibited heightened toxicity towards mouse eyes, seemingly due to oxidation enhances the interaction between virgin-MPs/modified-MPs and tissues/cells, and leading to the release of toxic substances increased. In conclusion, our discoveries demonstrate that oxidation exacerbates the harm of virgin-MPs to eyes, and are of great significance for evaluating the risk of MPs to ocular health.
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Affiliation(s)
- Ying Yang
- School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China
| | - Ji Wang
- School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China
| | - Yongpeng Shi
- School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China
| | - Hanwen Cao
- School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China
| | - Li Wei
- School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China; NHC Key Laboratory of Diagnosis and Therapy of Gastrointestinal Tumor, Gansu Provincial Hospital, Lanzhou, 730000, Gansu Province, China
| | - Lan Gao
- School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China.
| | - Mingxin Liu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, 730000, Gansu Province, China.
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Yang F, Yang Z, Zhao S, Huang Y. To Investigate the Changes in Corneal Curvature and Its Correlation with Corneal Epithelial Remodeling After Trans-PRK and FS-LASIK. Curr Eye Res 2024; 49:1061-1067. [PMID: 38867491 DOI: 10.1080/02713683.2024.2361728] [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: 09/08/2023] [Revised: 02/10/2024] [Accepted: 05/23/2024] [Indexed: 06/14/2024]
Abstract
PURPOSE To evaluate curvature changes in different regions and their correlation with corneal epithelial remodeling in myopic patients undergoing femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and transepithelial refractive keratectomy (Trans-PRK) after surgery. METHODS One hundred and sixty-three patients (163 right eyes) undergoing Trans-PRK and LASIK were evaluated for up to 6 months using anterior segment optical coherence tomography (OCT) to measure the epithelial thickness and corneal topography to measure corneal curvature in different areas (2 mm, 5 mm, and 7 mm). We calculated the curvature ΔK (ΔK = preoperative - postoperative), ΔK5-2 (ΔK5-2 = K5mm - K2mm), ΔK7-5 (ΔK7-5 = K7mm - K5mm), and the epithelial thickness ΔET5-2 (ΔET5-2 = ET5mm - ET2mm) and ΔET7-5 (ΔET7-5= ET7mm - ET5mm). RESULTS Corneal curvature flattened in each region of the two groups (all p < 0.001) and gradually steepened during the follow-up period. The Trans-PRK group flattened more significantly within 2 mm and 5 mm, while the FS-LASIK group at 7 mm. Both groups of ΔK decreased over time. Both groups of ΔK5-2 and ΔK7-5 gradually decreased during the follow-up period (P5-2=0.025 and P7-5 < 0.001 for Trans-PRK, P5-2 = 0.011 and P7-5 < 0.001 for FS-LASIK). The corneal epithelium of the two groups gradually thickened during the follow-up period, with Trans-PRK significantly thickening in the central and peripheral regions and FS-LASIK in the central and paracentral regions. There is a significant correlation between the ΔK5-2 and ΔET5-2, ΔK7-5 and ΔET7-5 (all r > 0.37, p < 0.001). CONCLUSIONS All groups showed significant curvature flattening after surgery and gradually steepening during the follow-up period. The corneal epithelium thickness in both groups of 17 regions became thicker,. In contrast, Trans-PRK group showed more significant thickening to the periphery and the central 5 mm area of the FS-LASIK. This study indicates a significant positive correlation between differences in epithelial thickening in different regions and differences in curvature changes in the corresponding areas PRK, FS-LASIK, curvature, corneal epithelial thickness.
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Affiliation(s)
- Fan Yang
- Eye Institute and School of Optometry, Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Zheng Yang
- Eye Institute and School of Optometry, Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Shaozhen Zhao
- Eye Institute and School of Optometry, Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Tianjin Medical University Eye Hospital, Tianjin, China
| | - Yue Huang
- Eye Institute and School of Optometry, Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Tianjin Medical University Eye Hospital, Tianjin, China
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Bucsan R, Coroleucă R, Garhöfer G, Popa-Cherecheanu A, Schmetterer L, Iancu R. Confocal Microscopy of the Cornea in Aqueous-Deficient Dry Eye Disease-A Literature Review. Diagnostics (Basel) 2024; 14:1613. [PMID: 39125489 PMCID: PMC11311367 DOI: 10.3390/diagnostics14151613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2024] [Revised: 07/22/2024] [Accepted: 07/23/2024] [Indexed: 08/12/2024] Open
Abstract
BACKGROUND In vivo confocal microscopy (IVCM) is a vital tool in studying dry eye disease (DED), providing insights into morphological changes at ocular surface unit levels. This review presents the main differences in corneal structure between aqueous-deficient dry eye disease (AD-DED) and normal eyes. METHODS A comprehensive search of PubMed, Web of Science, Embase, and MEDLINE databases from January 2000 to December 2023 was conducted. The study selection process, as well as data selection and examination, were independently performed by two members of the review team. RESULTS The review reveals a consistent decrease in corneal surface epithelial cell density in AD-DED cases compared to a control group, but conflicting data on basal epithelial cell density. Notably, the abnormal hyperreflectivity of keratocytes in patients with Sjogren's syndrome was recorded, and there was a significant keratocyte density in AD-DED subjects compared to evaporative DED and control groups. Studies also found a decrease in sub-basal nerve density, increased tortuosity, and the fragmentation of nerve fibers. Dendritic cell density and dendritic cell dendrites increase in AD-DED patients compared to healthy subjects. CONCLUSIONS IVCM is a powerful tool for enhancing our understanding of the pathophysiological mechanisms underlying DED. However, the review underscores the urgent need to standardize the terminology, analysis, and units used for accurate interpretation, a crucial step in advancing our knowledge of DED.
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Affiliation(s)
- Radu Bucsan
- Department of Ophthalmology, University of Medicine and Pharmacy Carol Davila, 050747 Bucharest, Romania; (R.B.); (R.C.); (R.I.)
| | - Ruxandra Coroleucă
- Department of Ophthalmology, University of Medicine and Pharmacy Carol Davila, 050747 Bucharest, Romania; (R.B.); (R.C.); (R.I.)
- Department of Ophthalmology, Emergency University Hospital Bucharest, 050098 Bucharest, Romania
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, 1090 Vienna, Austria;
| | - Alina Popa-Cherecheanu
- Department of Ophthalmology, University of Medicine and Pharmacy Carol Davila, 050747 Bucharest, Romania; (R.B.); (R.C.); (R.I.)
- Department of Ophthalmology, Emergency University Hospital Bucharest, 050098 Bucharest, Romania
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, 1090 Vienna, Austria;
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 168751, Singapore
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, National University of Singapore, Singapore 169857, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
- School of Chemical and Biological Engineering, Nanyang Technological University, Singapore 637371, Singapore
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, 1090 Vienna, Austria
- IOB—Institute of Molecular and Clinical Ophthalmology, 4031 Basel, Switzerland
- Fondation Ophtalmologique Adolphe De Rothschild, 75019 Paris, France
| | - Raluca Iancu
- Department of Ophthalmology, University of Medicine and Pharmacy Carol Davila, 050747 Bucharest, Romania; (R.B.); (R.C.); (R.I.)
- Department of Ophthalmology, Emergency University Hospital Bucharest, 050098 Bucharest, Romania
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Sun Z, Lu K, He Q, Tang Y, Li H, Pazo EE, Hu L, Wei R. INOS ablation promotes corneal wound healing via activation of Akt signaling. Exp Eye Res 2024; 243:109886. [PMID: 38583755 DOI: 10.1016/j.exer.2024.109886] [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: 12/22/2023] [Revised: 03/24/2024] [Accepted: 04/04/2024] [Indexed: 04/09/2024]
Abstract
Corneal injury leads to impaired normal structure of the cornea. Improving the wound healing process in epithelial cells significantly contributes to ocular damage treatments. Here, we aimed to investigate the potential mechanisms of nitric oxide (NO) and its mediator, inducible nitric oxide synthase (iNOS), in the process of corneal wound healing. We established a corneal injury model of iNOS-/- mice, and treated human corneal epithelial cell lines (HCE-2) with the iNOS inhibitor L-INL, with or without NO replenishment by supplying sodium nitroferricyanide dihydrate (SNP). Our findings showed that inhibition of NO/iNOS accelerated corneal repair, enhanced uPAR (a receptor protein indicating the migration ability), and improved epithelial cell migration. Furthermore, NO/iNOS ablation activated Akt phosphorylation, reduced neutrophil marker protein MPO expression, and downregulated the transcription of inflammation cytokines CXCL-1, CXCL-2, IL-1β, IL-6, and TNF-α. However, the protective effects of NO/iNOS inhibition are significantly reduced by NO replenishment when treated with SNP. Therefore, we confirmed that inhibiting NO/iNOS improved the corneal wound healing by facilitating epithelial cell migration and reducing inflammatory reactions, which might be related to the activation of the Akt signaling pathway.
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Affiliation(s)
- Ziwen Sun
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 300070, Tianjin, China
| | - Kunpeng Lu
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, 300070, Tianjin, China
| | - Qing He
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 300070, Tianjin, China
| | - Yang Tang
- Qingdao State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong Academy of Medical Sciences, 266071, Qingdao, China
| | - Haoru Li
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 300070, Tianjin, China
| | - Emmanuel Eric Pazo
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 300070, Tianjin, China
| | - Lizhi Hu
- Basic Medical College, Immunology Department, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, 300070, China.
| | - Ruihua Wei
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, 300070, Tianjin, China.
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5
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Lenze M, Benedetti MD, Roco J, Ramírez PG, Blanco R, Yaceszen S, Corrales C, Wikinski S, Gutiérrez ML. Advancing ocular safety research: A comprehensive examination of benzocaine acute exposure without animal testing. Toxicol Lett 2024; 394:138-145. [PMID: 38458340 DOI: 10.1016/j.toxlet.2024.03.003] [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: 12/04/2023] [Revised: 03/01/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Benzocaine is a widely employed local anaesthetic; however, there is a notable dearth of preclinical and clinical evidence regarding its safety in ophthalmological products. To address this, a comprehensive strategy incorporating in silico and in vitro methodologies was proposed for assessing benzocaine's ocular toxicity without animal testing. To collect the in silico evidence, the QSAR Toolbox (v4.5) was used. A single exposure to two benzocaine concentrations (2% and 20%) was evaluated by in vitro methods. Hen's Egg Chorioallantoic Membrane Test (HET-CAM) was performed to evaluate the effects on the conjunctiva. To study corneal integrity, Short Time Exposure test (STE) and Bovine Corneal Opacity and Permeability (BCOP) assay, followed by histopathological analysis, were carried out. Results from both in silico and in vitro methodologies categorize benzocaine as non-irritating. The histopathological analysis further affirms the safety of using benzocaine in eye drops, as no alterations were observed in evaluated corneal strata. This research proposes a useful combined strategy to provide evidence on the safety of local anaesthetics and particularly show that 2% and 20% benzocaine solutions do not induce eye irritation or corneal damage, supporting the potential use of benzocaine in the development of ophthalmic anesthetic products.
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Affiliation(s)
- M Lenze
- Instituto de Farmacología, Universidad de Buenos Aires, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - M D Benedetti
- Instituto de Farmacología, Universidad de Buenos Aires, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - J Roco
- Instituto de Farmacología, Universidad de Buenos Aires, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - P G Ramírez
- Instituto de Farmacología, Universidad de Buenos Aires, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | | | | | | | - S Wikinski
- Instituto de Farmacología, Universidad de Buenos Aires, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - M L Gutiérrez
- Instituto de Farmacología, Universidad de Buenos Aires, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.
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Kleinbeck S, Wolkoff P. Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors. Arch Toxicol 2024; 98:617-662. [PMID: 38243103 PMCID: PMC10861400 DOI: 10.1007/s00204-023-03642-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 11/16/2023] [Indexed: 01/21/2024]
Abstract
Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.
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Affiliation(s)
- Stefan Kleinbeck
- Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany.
| | - Peder Wolkoff
- National Research Centre for the Working Environment, Copenhagen, Denmark
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7
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Lu X, Chen Z, Lu J, Watsky MA. Effects of 1,25-Vitamin D3 and 24,25-Vitamin D3 on Corneal Nerve Regeneration in Diabetic Mice. Biomolecules 2023; 13:1754. [PMID: 38136625 PMCID: PMC10742127 DOI: 10.3390/biom13121754] [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: 11/07/2023] [Revised: 11/30/2023] [Accepted: 12/02/2023] [Indexed: 12/24/2023] Open
Abstract
Corneal nerve homeostasis is essential for the functional integrity of the ocular surface. Vitamin D deficiency (VDD) and vitamin D receptor knockout (VDR KO) have been found to reduce corneal nerve density in diabetic mice. This is the first study to comprehensively examine the influence of vitamin D on nerve regeneration following corneal epithelial injury in diabetic mice. Corneal nerve regeneration was significantly retarded by diabetes, VDR KO, and VDD, and it was accelerated following topical 1,25 Vit D and 24,25 Vit D administration. Furthermore, topical 1,25 Vit D and 24,25 Vit D increased nerve growth factor, glial cell line-derived neurotropic factor, and neurotropin-3 protein expression, and it increased secretion of GDNF protein from human corneal epithelial cells. CD45+ cells and macrophage numbers were significantly decreased, and vitamin D increased CD45+ cell and macrophage recruitment in these wounded diabetic mouse corneas. The accelerated nerve regeneration observed in these corneas following topical 1,25 Vit D and 24,25 Vit D administration may be related to the vitamin D-stimulated expression, secretion of neurotrophic factors, and recruitment of immune cells.
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Affiliation(s)
- Xiaowen Lu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, CB-2901, Augusta, GA 30912, USA
| | | | | | - Mitchell A. Watsky
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1120 15th Street, CB-2901, Augusta, GA 30912, USA
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8
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Lin X, Xu P, Tian Y, Xiao H, Dong X, Wang S. Establishing a Mouse Model of Chlorpromazine-Induced Corneal Trigeminal Denervation. Transl Vis Sci Technol 2023; 12:21. [PMID: 37906054 PMCID: PMC10619696 DOI: 10.1167/tvst.12.10.21] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 09/24/2023] [Indexed: 11/02/2023] Open
Abstract
Purpose This study aimed to establish a mouse model of chlorpromazine-induced corneal trigeminal denervation (CCTD). Methods Retrobulbar chlorpromazine injections were administered to 6- to 8-week-old C57BL/6j mice to induce corneal denervation. Additionally, apoptosis was assessed in isolated primary trigeminal ganglion cells after culturing in a conditioned medium containing chlorpromazine. Finally, the success rate of model generation, mortality and complication rates, and model-preparation learning curves were compared between the CCTD model and the electrocoagulation and axotomy models. Results Chlorpromazine retrobulbar injections resulted in trigeminal denervation, leading to a reduced blink reflex, corneal nerve density, and corneal epithelium thickness. Furthermore, 90% (9/10) of the mice developed epithelial defects, accompanied by increased apoptosis and inhibited proliferation of corneal epithelial cells. In vitro, trigeminal ganglion cell apoptosis increased after culturing in a conditioned medium containing chlorpromazine. Moreover, the CCTD model exhibited a higher success rate, longer survival rate, and lower complication rate compared to the electrocoagulation and axotomy models. Crucially, the learning curve demonstrated that the method used to generate the CCTD model was easy to learn. Conclusions The CCTD model is a user-friendly mouse model for studying corneal trigeminal denervation that offers a less invasive alternative to existing models. Translational Relevance The CCTD model serves as a valuable tool for investigating the functional mechanisms of corneal trigeminal nerves and their interactions with corneal cells.
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Affiliation(s)
- Xiongshi Lin
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Peipei Xu
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Ying Tian
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Haiqi Xiao
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Xing Dong
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Shuangyong Wang
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
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9
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Alemi H, Dehghani S, Musayeva A, Nadari A, Narimatsu A, Sharifi S, Forouzanfar K, Wang S, Dohlman TH, Yin J, Chen Y, Dana R. Insights into mustard gas keratopathy: Characterizing corneal layer-specific changes in mice exposed to nitrogen mustard. Exp Eye Res 2023:109495. [PMID: 37142048 DOI: 10.1016/j.exer.2023.109495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/20/2023] [Accepted: 05/02/2023] [Indexed: 05/06/2023]
Abstract
Exposure to mustard agents, such as sulfur mustard (SM) and nitrogen mustard (NM), often results in ocular surface damage. This can lead to the emergence of various corneal disorders that are collectively referred to as mustard gas keratopathy (MGK). In this study, we aimed to develop a mouse model of MGK by using ocular NM exposure, and describe the subsequent structural changes analyzed across the different layers of the cornea. A 3 μL solution of 0.25 mg/mL NM was applied to the center of the cornea via a 2-mm filter paper for 5 min. Mice were evaluated prior to and after exposure on days 1 and 3, and weekly for 4 weeks using slit lamp examination with fluorescein staining. Anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM) tracked changes in the epithelium, stroma, and endothelium of the cornea. Histologic evaluation and immunostaining were used to examine corneal cross-sections collected at the completion of follow-up. A biphasic ocular injury was observed in mice exposed to NM, most prominent in the corneal epithelium and anterior stroma. Following exposure, mice experienced central corneal epithelial erosions and thinning, accompanied by a decreased number of nerve branches in the subbasal plexus and increased activated keratocytes in the stroma. The epithelium was recovered by day 3, followed by exacerbated punctuate erosions alongside persistent stromal edema that arose and continued onward to four weeks post-exposure. The endothelial cell density was reduced on the first day after NM exposure, which persisted until the end of follow-up, along with increased polymegethism and pleomorphism. Microstructural changes in the central cornea at this time included dysmorphic basal epithelial cells, and in the limbal cornea included decreased cellular layers and p63+ area, along with increased DNA oxidization. We present a mouse model of MGK using NM that successfully replicates ocular injury caused by SM in humans who have been exposed to mustard gas. Our research suggests DNA oxidation contributes to the long-term effects of nitrogen mustard on limbal stem cells.
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Affiliation(s)
- Hamid Alemi
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Shima Dehghani
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Aytan Musayeva
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Amirreza Nadari
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Akitomo Narimatsu
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Sina Sharifi
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Katayoun Forouzanfar
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Shudan Wang
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Thomas H Dohlman
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Jia Yin
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Yihe Chen
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
| | - Reza Dana
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
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10
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Zhang J, Lin H, Li F, Wu K, Yang S, Zhou S. Involvement of endoplasmic reticulum stress in trigeminal ganglion corneal neuron injury in dry eye disease. Front Mol Neurosci 2023; 16:1083850. [PMID: 37033374 PMCID: PMC10080667 DOI: 10.3389/fnmol.2023.1083850] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 03/13/2023] [Indexed: 04/11/2023] Open
Abstract
Dry eye disease (DED) is a multifactorial disease with a high prevalence worldwide. Uncomfortable corneal sensations severely affect daily life in DED patients. Hence, corneal neuron injury is a vital pathogenesis in DED. Notably, endoplasmic reticulum stress (ERS) plays a role in peripheral neuron injury. However, the role of ERS in DED corneal neuron injury is still far from being clear. In this study, we established an environmental DED (eDED) model in vivo and a hyperosmotic DED model in vitro. Subsequently, trigeminal ganglion (TG) corneal neurons were retrograde labeled by WGA-Alexa Fluor 555, and fluorescence-activated cell sorting was used to collect targeted corneal neurons for RNA sequencing in mice. Our results revealed that TG corneal neuron injury but not apoptosis in DED. ERS-related genes and proteins were upregulated in TG corneal neurons of the eDED mice. ERS inhibition alleviated TG corneal neuron's ERS-related injury. Therefore, ERS-induced TG corneal neuron injury may be an important pathomechanism and provide a promising therapeutic approach to DED.
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Affiliation(s)
- Jinyu Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Hongbin Lin
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou, China
| | - Fengxian Li
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou, China
| | - Kaili Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Shuangjian Yang
- Guangdong Institute for Vision and Eye Research, Guangzhou, China
| | - Shiyou Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
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11
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Mörö A, Samanta S, Honkamäki L, Rangasami VK, Puistola P, Kauppila M, Narkilahti S, Miettinen S, Oommen O, Skottman H. Hyaluronic acid based next generation bioink for 3D bioprinting of human stem cell derived corneal stromal model with innervation. Biofabrication 2022; 15. [PMID: 36579828 DOI: 10.1088/1758-5090/acab34] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022]
Abstract
Corneal transplantation remains gold standard for the treatment of severe cornea diseases, however, scarcity of donor cornea is a serious bottleneck. 3D bioprinting holds tremendous potential for cornea tissue engineering (TE). One of the key technological challenges is to design bioink compositions with ideal printability and cytocompatibility. Photo-crosslinking and ionic crosslinking are often used for the stabilization of 3D bioprinted structures, which can possess limitations on biological functionality of the printed cells. Here, we developed a hyaluronic acid-based dopamine containing bioink using hydrazone crosslinking chemistry for the 3D bioprinting of corneal equivalents. First, the shear thinning property, viscosity, and mechanical stability of the bioink were optimized before extrusion-based 3D bioprinting for the shape fidelity and self-healing property characterizations. Subsequently, human adipose stem cells (hASCs) and hASC-derived corneal stromal keratocytes were used for bioprinting corneal stroma structures and their cell viability, proliferation, microstructure and expression of key proteins (lumican, vimentin, connexin 43,α-smooth muscle actin) were evaluated. Moreover, 3D bioprinted stromal structures were implanted intoex vivoporcine cornea to explore tissue integration. Finally, human pluripotent stem cell derived neurons (hPSC-neurons), were 3D bioprinted to the periphery of the corneal structures to analyze innervation. The bioink showed excellent shear thinning property, viscosity, printability, shape fidelity and self-healing properties with high cytocompatibility. Cells in the printed structures displayed good tissue formation and 3D bioprinted cornea structures demonstrated excellentex vivointegration to host tissue as well asin vitroinnervation. The developed bioink and the printed cornea stromal equivalents hold great potential for cornea TE applications.
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Affiliation(s)
- Anni Mörö
- Eye Regeneration Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland
| | - Sumanta Samanta
- Bioengineering and Nanomedicine Lab, Faculty of Medicine and Health Technology, University, Tampere 33720, Finland
| | - Laura Honkamäki
- Neuro Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland
| | - Vignesh K Rangasami
- Bioengineering and Nanomedicine Lab, Faculty of Medicine and Health Technology, University, Tampere 33720, Finland
| | - Paula Puistola
- Eye Regeneration Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland
| | - Maija Kauppila
- Eye Regeneration Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland
| | - Susanna Narkilahti
- Neuro Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland
| | - Susanna Miettinen
- Adult Stem Cell Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland.,Research, Development and Innovation Centre, Tampere University Hospital, Tampere 33520, Finland
| | - Oommen Oommen
- Bioengineering and Nanomedicine Lab, Faculty of Medicine and Health Technology, University, Tampere 33720, Finland
| | - Heli Skottman
- Eye Regeneration Group, Faculty of Medicine and Health Technology, Tampere University, Tampere 33520, Finland
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12
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Nieto-Aristizábal I, Mera JJ, Giraldo JD, Lopez-Arevalo H, Tobón GJ. From ocular immune privilege to primary autoimmune diseases of the eye. Autoimmun Rev 2022; 21:103122. [DOI: 10.1016/j.autrev.2022.103122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/02/2022] [Indexed: 11/17/2022]
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13
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TRPV1 + sensory nerves modulate corneal inflammation after epithelial abrasion via RAMP1 and SSTR5 signaling. Mucosal Immunol 2022; 15:867-881. [PMID: 35680973 DOI: 10.1038/s41385-022-00533-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 04/25/2022] [Accepted: 05/24/2022] [Indexed: 02/04/2023]
Abstract
Timely initiation and termination of inflammatory response after corneal epithelial abrasion is critical for the recovery of vision. The cornea is innervated with rich sensory nerves with highly dense TRPV1 nociceptors. However, the roles of TRPV1+ sensory neurons in corneal inflammation after epithelial abrasion are not completely understood. Here, we found that depletion of TRPV1+ sensory nerves using resiniferatoxin (RTX) and blockade of TRPV1 using AMG-517 delayed corneal wound closure and enhanced the infiltration of neutrophils and γδ T cells to the wounded cornea after epithelial abrasion. Furthermore, depletion of TRPV1+ sensory nerves increased the number and TNF-α production of corneal CCR2+ macrophages and decreased the number of corneal CCR2- macrophages and IL-10 production. In addition, the TRPV1+ sensory nerves inhibited the recruitment of neutrophils and γδ T cells to the cornea via RAMP1 and SSTR5 signaling, decreased the responses of CCR2+ macrophages via RAMP1 signaling, and increased the responses of CCR2- macrophages via SSTR5 signaling. Collectively, our results suggest that the TRPV1+ sensory nerves suppress inflammation to support corneal wound healing via RAMP1 and SSTR5 signaling, revealing potential approaches for improving defective corneal wound healing in patients with sensory neuropathy.
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14
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Corneal stromal repair and regeneration. Prog Retin Eye Res 2022; 91:101090. [DOI: 10.1016/j.preteyeres.2022.101090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 01/02/2023]
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15
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Wu F, Zhao Y, Zhang H. Ocular Autonomic Nervous System: An Update from Anatomy to Physiological Functions. Vision (Basel) 2022; 6:vision6010006. [PMID: 35076641 PMCID: PMC8788436 DOI: 10.3390/vision6010006] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 11/16/2022] Open
Abstract
The autonomic nervous system (ANS) confers neural control of the entire body, mainly through the sympathetic and parasympathetic nerves. Several studies have observed that the physiological functions of the eye (pupil size, lens accommodation, ocular circulation, and intraocular pressure regulation) are precisely regulated by the ANS. Almost all parts of the eye have autonomic innervation for the regulation of local homeostasis through synergy and antagonism. With the advent of new research methods, novel anatomical characteristics and numerous physiological processes have been elucidated. Herein, we summarize the anatomical and physiological functions of the ANS in the eye within the context of its intrinsic connections. This review provides novel insights into ocular studies.
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16
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Surnina ZV, Andreev AY, Sharnina DA, Yusef SN. [Nerve fiber structure after different types of corneal transplantation]. Vestn Oftalmol 2022; 138:260-265. [PMID: 36287165 DOI: 10.17116/oftalma2022138052260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This review presents basic information about the state of corneal nerve fibers and Langerhans cells before and after keratoplasty. Keratoplasty is a common corneal surgery that carries a risk of graft rejection. The state of corneal nerve fibers can vary after different types of keratoplasty. Corneal confocal microscopy allows in vivo evaluation of the cornea, which can help assess the condition of corneal nerve fibers, as well as reveal the presence of Langerhans cells. Further research in this direction would contribute to identifying the relationship between the state of corneal nerve fibers, the presence of Langerhans cells, and graft rejection.
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Affiliation(s)
- Z V Surnina
- Research Institute of Eye Disease, Moscow, Russia
| | - A Yu Andreev
- Research Institute of Eye Disease, Moscow, Russia.,I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | - D A Sharnina
- Research Institute of Eye Disease, Moscow, Russia
| | - S N Yusef
- Research Institute of Eye Disease, Moscow, Russia
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17
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Wang L, Zhang Y, Wei Z, Cao K, Su G, Hamrah P, Labbe A, Liang Q. Characteristics of Toxic Keratopathy, an In Vivo Confocal Microscopy Study. Transl Vis Sci Technol 2021; 10:11. [PMID: 34495329 PMCID: PMC8431974 DOI: 10.1167/tvst.10.11.11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Purpose Toxic keratopathy (TK) involves complex clinical manifestations and is difficult to differentiate from other ocular surface diseases by conventional slit-lamp examination. The challenge faced by clinicians in confidently diagnosing TK cannot be underestimated. This study aimed to explore the microstructural characteristics and diagnostic parameters by in vivo confocal microscopy (IVCM) in TK. Methods In this prospective, cross-sectional, comparative study, slit-lamp and IVCM examinations were performed on 20 normal eyes and 54 eyes with TK. Based on slit-lamp imaging, TK subjects were divided into four groups: superficial punctate keratitis (n = 10 eyes), pseudodendritic keratitis (n = 14 eyes), ulcerative keratitis (UK; n = 16 eyes), and ring keratitis (RK; n = 14 eyes). The microstructural characteristics of TK were described according to the following IVCM parameters: basal cell (BC) density, dendritiform cell (DC) density, DC size, corneal nerve fiber (CNF) length, nerve tortuosity, and keratocyte reflectivity. A receiver operating characteristic (ROC) curve model was also formulated to compare the predictive power of BC density, DC density, and CNF length. Results TK eyes showed significantly higher values for DC density (45.8 cells/mm2; range, 25.0–100.0) compared with normal eyes (24.0 cells/mm2; range, 20.8–32.3; P = 0.013; DC size (111.0 µm2; range, 92.0–137.8) compared with normal eyes (63.7 µm2; range, 47.7–70.3; P < 0.001); nerve tortuosity (0.08; range, 0.05–0.09) compared with normal eyes (0.04; range, 0.02–0.04; P < 0.001); and keratocyte reflectivity. BC density and CNF length values were found to be significantly less than those for normal controls (both P < 0.001). In all subgroups, CNF length appeared to be significantly lower than that of controls (all P < 0.001), and DC density was only statistically significantly higher in the UK (P = 0.003) and RK (P < 0.001) groups. Corneal fluorescein staining had no correlation with the analyzed IVCM parameters (all P ˃ 0.05). However, the increase in DC density and DC size showed negative correlations to CNF length (density: r = −0.325, P < 0.005; size: r = −0.493, P < 0.005), as well as positive correlations to duration and frequency of topical eye drops and DC size (density: r = 0.361, P < 0.05; size: r = 0.581, P < 0.05). A ROC curve showed that CNF length had the strongest predictive power, with the estimated area under the curve being 0.992 ± 0.008. Conclusions Lower BC density and CNF length, greater DC density and DC size, and greater keratocyte reflectivity were the microstructural characteristics of TK. The role of subbasal nerve, inflammatory response, and limbal stem cells in the progression of TK and the appropriate treatment of different TK stages are future research directions. Translational Relevance The evaluation of basal cells, subbasal nerve, and dendritiform cells is helpful to our understanding of the pathological process of TK.
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Affiliation(s)
- Leying Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yang Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Zhenyu Wei
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Kai Cao
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Guanyu Su
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Pedram Hamrah
- Cornea Service, New England Eye Center, Center for Translational Ocular Immunology, Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - Antoine Labbe
- Quinze-Vingts National Ophthalmology Hospital, IHU FOReSIGHT, Paris and Versailles Saint-Quentin-en-Yvelines University, Versailles, France.,Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Qingfeng Liang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing Tongren Hospital, Capital Medical University, Beijing, China
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18
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Teus MA, Garcia-Gonzalez M. Corneal Denervation After SMILE Versus LASIK. J Refract Surg 2021; 37:504. [PMID: 34236910 DOI: 10.3928/1081597x-20210427-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Atypical Cellular Elements of Unknown Origin in the Subbasal Nerve Plexus of a Diabetic Cornea Diagnosed by Large-Area Confocal Laser Scanning Microscopy. Diagnostics (Basel) 2021; 11:diagnostics11020154. [PMID: 33494468 PMCID: PMC7911241 DOI: 10.3390/diagnostics11020154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/17/2022] Open
Abstract
In vivo large-area confocal laser scanning microscopy (CLSM) of the human eye using EyeGuidance technology allows a large-scale morphometric assessment of the corneal subbasal nerve plexus (SNP). Here, the SNP of a patient suffering from diabetes and associated late complications was analyzed. The SNP contained multiple clusters of large hyperintense, stellate-shaped, cellular-like structures. Comparable structures were not observed in control corneas from healthy volunteers. Two hypotheses regarding the origin of these atypical structures are proposed. First, these structures might be keratocyte-derived myofibroblasts that entered the epithelium from the underlying stroma through breaks in Bowman’s layer. Second, these structures could be proliferating Schwann cells that entered the epithelium in association with subbasal nerves. The nature and pathophysiological significance of these atypical cellular structures, and whether they are a direct consequence of the patient’s diabetic neuropathy/or a non-specific secondary effect of associated inflammatory processes, are unknown.
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