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Abu-Romman A, Scholand KK, Govindarajan G, Yu Z, Pal-Ghosh S, Stepp MA, de Paiva CS. Age-Related Differences in the Mouse Corneal Epithelial Transcriptome and Their Impact on Corneal Wound Healing. Invest Ophthalmol Vis Sci 2024; 65:21. [PMID: 38739085 PMCID: PMC11098051 DOI: 10.1167/iovs.65.5.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/24/2024] [Indexed: 05/14/2024] Open
Abstract
Purpose Aging is a risk factor for dry eye. We sought to identify changes in the aged mouse corneal epithelial transcriptome and determine how age affects corneal sensitivity, re-epithelialization, and barrier reformation after corneal debridement. Methods Corneal epithelium of female C57BL/6J (B6) mice of different ages (2, 12, 18, and 24 months) was collected, RNA extracted, and bulk RNA sequencing performed. Cornea sensitivity was measured with an esthesiometer in 2- to 3-month-old, 12- to 13-month-old, 18- to 19-month-old, and 22- to 25-month-old female and male mice. The 2-month-old and 18-month-old female and male mice underwent unilateral corneal debridement using a blunt blade. Wound size and fluorescein staining were visualized and photographed at different time points, and a re-epithelialization rate curve was calculated. Results There were 157 differentially expressed genes in aged mice compared with young mice. Several pathways downregulated with age control cell migration, proteoglycan synthesis, and collagen trimerization, assembly, biosynthesis, and degradation. Male mice had decreased corneal sensitivity compared with female mice at 12 and 24 months of age. Aged mice, irrespective of sex, had delayed corneal re-epithelialization in the first 48 hours and worse corneal fluorescein staining intensity at day 14 than young mice. Conclusions Aged corneal epithelium has an altered transcriptome. Aged mice regardless of sex heal more slowly and displayed more signs of corneal epithelial defects after wounding than young mice. These results indicate that aging significantly alters the corneal epithelium and its ability to coordinate healing.
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Affiliation(s)
- Anmar Abu-Romman
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Kaitlin K. Scholand
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
- Department of Biosciences, Rice University, Houston, Texas, United States
| | - Gowthaman Govindarajan
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Zhiyuan Yu
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Sonali Pal-Ghosh
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Mary A. Stepp
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
- Department of Ophthalmology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Cintia S. de Paiva
- Ocular Surface Center, Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
- Department of Biosciences, Rice University, Houston, Texas, United States
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Bazan HEP, Pham TL. A new R,R-RvD6 isomer with protective actions following corneal nerve injury. Prostaglandins Other Lipid Mediat 2024; 170:106802. [PMID: 38036037 DOI: 10.1016/j.prostaglandins.2023.106802] [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: 09/15/2023] [Revised: 11/05/2023] [Accepted: 11/27/2023] [Indexed: 12/02/2023]
Abstract
The transparent cornea is the most densely innervated tissue in the body, primarily by sensory nerves originating from the trigeminal ganglia (TG). Damage to corneal nerves reduces sensitivity and tear secretion and results in dry eye. Consequently, ocular pain, for which no satisfactory therapies exist, arises in many cases. Treatment of injured corneas with pigment epithelium-derived factor (PEDF) combined with docosahexaenoic acid (DHA) stimulates nerve regeneration in models of refractive surgery, which damages nerves. The mechanism involves the synthesis of a stereoisomer of resolvin D6 (R,R-RvD6) formed after incorporating DHA into membrane lipids. Activation of a PEDF receptor (PEDF-R) with phospholipase activity releases DHA to synthesize the new resolvin isomer, which is secreted via tears. Topical treatment of mice corneas with R,R-RvD6 shows higher bioactivity in regenerating nerves and increasing sensitivity compared to PEDF+DHA. It also stimulates a transcriptome in the TG that modulates genes involved in ocular pain. Our studies suggest an important therapeutic role for R,R-RvD6 in regenerating corneal nerves and decreasing pain resulting from dry eye.
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Affiliation(s)
- Haydee E P Bazan
- Neuroscience Center of Excellence and Department of Ophthalmology, School of Medicine, Louisiana State University Health Sciences Center New Orleans, New Orleans, LA, USA.
| | - Thang L Pham
- Neuroscience Center of Excellence and Department of Ophthalmology, School of Medicine, Louisiana State University Health Sciences Center New Orleans, New Orleans, LA, USA.
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Hadvina R, Estes A, Liu Y. Animal Models for the Study of Keratoconus. Cells 2023; 12:2681. [PMID: 38067109 PMCID: PMC10705680 DOI: 10.3390/cells12232681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/03/2023] [Accepted: 11/15/2023] [Indexed: 12/18/2023] Open
Abstract
Keratoconus (KC) is characterized by localized, central thinning and cone-like protrusion of the cornea. Its precise etiology remains undetermined, although both genetic and environmental factors are known to contribute to disease susceptibility. Due to KC's complex nature, there is currently no ideal animal model to represent both the corneal phenotype and underlying pathophysiology. Attempts to establish a KC model have involved mice, rats, and rabbits, with some additional novel animals suggested. Genetic animal models have only been attempted in mice. Similarly, spontaneously occurring animal models for KC have only been discovered in mice. Models generated using chemical or environmental treatments have been attempted in mice, rats, and rabbits. Among several methods used to induce KC in animals, ultraviolet radiation exposure and treatment with collagenase are some of the most prevalent. There is a clear need for an experimental model animal to elucidate the underlying mechanisms behind the development and progression of keratoconus. An appropriate animal model could also aid in the development of treatments to slow or arrest the disorder.
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Affiliation(s)
- Rachel Hadvina
- Department of Cellular Biology & Anatomy, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
- Center for Biotechnology and Genomic Medicine, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
| | - Amy Estes
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA
| | - Yutao Liu
- Department of Cellular Biology & Anatomy, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
- Center for Biotechnology and Genomic Medicine, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA 30912, USA
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4
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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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Hu B, Lv X, Wei L, Wang Y, Zheng G, Yang C, Zang F, Wang J, Li J, Wu X, Yue Z, Xiao Q, Shao Z, Yuan W, Li J, Cao P, Xu C, Chen H. Sensory Nerve Maintains Intervertebral Disc Extracellular Matrix Homeostasis Via CGRP/CHSY1 Axis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2202620. [PMID: 36047655 PMCID: PMC9596848 DOI: 10.1002/advs.202202620] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/22/2022] [Indexed: 06/01/2023]
Abstract
Sensory nerves are long being recognized as collecting units of various outer stimuli; recent advances indicate that the sensory nerve also plays pivotal roles in maintaining organ homeostasis. Here, this study shows that sensory nerve orchestrates intervertebral disc (IVD) homeostasis by regulating its extracellular matrix (ECM) metabolism. Specifically, genetical sensory denervation of IVD results in loss of IVD water preserve molecule chondroitin sulfate (CS), the reduction of CS bio-synthesis gene chondroitin sulfate synthase 1 (CHSY1) expression, and dysregulated ECM homeostasis of IVD. Particularly, knockdown of sensory neuros calcitonin gene-related peptide (CGRP) expression induces similar ECM metabolic disorder compared to sensory nerve denervation model, and this effect is abolished in CHSY1 knockout mice. Furthermore, in vitro evidence shows that CGRP regulates nucleus pulposus cell CHSY1 expression and CS synthesis via CGRP receptor component receptor activity-modifying protein 1 (RAMP1) and cyclic AMP response element-binding protein (CREB) signaling. Therapeutically, local injection of forskolin significantly attenuates IVD degeneration progression in mouse annulus fibrosus puncture model. Overall, these results indicate that sensory nerve maintains IVD ECM homeostasis via CGRP/CHSY1 axis and promotes IVD repair, and this expands the understanding concerning how IVD links to sensory nerve system, thus shedding light on future development of novel therapeutical strategy to IVD degeneration.
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Affiliation(s)
- Bo Hu
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Xiao Lv
- Department of OrthopaedicsUnion HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430022China
| | - Leixin Wei
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Yunhao Wang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Genjiang Zheng
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Chen Yang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Fazhi Zang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Jianxi Wang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Jing Li
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Xiaodong Wu
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Zhihao Yue
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Qiangqiang Xiao
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Zengwu Shao
- Department of OrthopaedicsUnion HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430022China
| | - Wen Yuan
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Jinsong Li
- State Key Laboratory of Cell BiologyShanghai Key Laboratory of Molecular AndrologyCAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell BiologyChinese Academy of ScienceShanghai200031China
| | - Peng Cao
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Chen Xu
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Huajiang Chen
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
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He J, Pham TL, Bazan HEP. Neuroanatomy of Adult and Aging Chicken Cornea. Curr Eye Res 2022; 47:1374-1380. [PMID: 35904450 PMCID: PMC9844890 DOI: 10.1080/02713683.2022.2104321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/05/2022] [Accepted: 07/15/2022] [Indexed: 01/19/2023]
Abstract
PURPOSE To provide a complete nerve architecture and main sensory neuropeptide distribution in the chicken cornea. METHODS Adult chickens aged 6 months and 4 years were used. The whole cornea was stained with protein gene product (PGP) 9.5 antibody-a pan marker for nerve fibers, calcitonin gene-related peptide (CGRP), and substance P (SP) antibodies; whole-mount images were acquired to build an entire view of corneal innervation. Relative corneal epithelial nerve fiber densities, including subbasal bundles and superficial terminals, were assessed by computer-assisted analysis. RESULTS An average of about 76.3 ± 5.7 (n = 8 corneas, 4 M/4F) stromal nerve trunks enter the cornea radially and are evenly distributed around the limbus with no significant difference between male and female chickens. The subbasal nerve bundles do not extend in a given direction and, as a result, do not form a vortex in the center of the cornea. Furthermore, the chicken cornea contains more SP-positive nerves than CGRP-positive nerves. It is also shown that aging significantly reduces corneal epithelial nerve density in chickens. CONCLUSIONS This is the first study to provide a complete map of the entire corneal nerves and CGRP and SP sensory neuropeptide distribution in the adult chicken cornea. The findings show chicken corneal innervation has many differences to human and mammal cornea.
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Affiliation(s)
- Jiucheng He
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
- Department of Ophthalmology, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Thang Luong Pham
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
| | - Haydee E. P. Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
- Department of Ophthalmology, School of Medicine, Louisiana State University Health New Orleans, New Orleans, USA
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Puri S, Kenyon BM, Hamrah P. Immunomodulatory Role of Neuropeptides in the Cornea. Biomedicines 2022; 10:1985. [PMID: 36009532 PMCID: PMC9406019 DOI: 10.3390/biomedicines10081985] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 12/21/2022] Open
Abstract
The transparency of the cornea along with its dense sensory innervation and resident leukocyte populations make it an ideal tissue to study interactions between the nervous and immune systems. The cornea is the most densely innervated tissue of the body and possesses both immune and vascular privilege, in part due to its unique repertoire of resident immune cells. Corneal nerves produce various neuropeptides that have a wide range of functions on immune cells. As research in this area expands, further insights are made into the role of neuropeptides and their immunomodulatory functions in the healthy and diseased cornea. Much remains to be known regarding the details of neuropeptide signaling and how it contributes to pathophysiology, which is likely due to complex interactions among neuropeptides, receptor isoform-specific signaling events, and the inflammatory microenvironment in disease. However, progress in this area has led to an increase in studies that have begun modulating neuropeptide activity for the treatment of corneal diseases with promising results, necessitating the need for a comprehensive review of the literature. This review focuses on the role of neuropeptides in maintaining the homeostasis of the ocular surface, alterations in disease settings, and the possible therapeutic potential of targeting these systems.
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Affiliation(s)
- Sudan Puri
- Center for Translational Ocular Immunology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA
- Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Brendan M. Kenyon
- Center for Translational Ocular Immunology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Pedram Hamrah
- Center for Translational Ocular Immunology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA
- Department of Ophthalmology, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA
- Program in Neuroscience, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
- Departments of Immunology and Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
- Cornea Service, Tufts New England Eye Center, Boston, MA 02111, USA
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8
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Neuroimmune crosstalk in the cornea: The role of immune cells in corneal nerve maintenance during homeostasis and inflammation. Prog Retin Eye Res 2022; 91:101105. [PMID: 35868985 DOI: 10.1016/j.preteyeres.2022.101105] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/01/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022]
Abstract
In the cornea, resident immune cells are in close proximity to sensory nerves, consistent with their important roles in the maintenance of nerves in both homeostasis and inflammation. Using in vivo confocal microscopy in humans, and ex vivo immunostaining and fluorescent reporter mice to visualize corneal sensory nerves and immune cells, remarkable progress has been made to advance our understanding of the physical and functional interactions between corneal nerves and immune cells. In this review, we summarize and discuss recent studies relating to corneal immune cells and sensory nerves, and their interactions in health and disease. In particular, we consider how disrupted corneal nerve axons can induce immune cell activity, including in dendritic cells, macrophages and other infiltrating cells, directly and/or indirectly by releasing neuropeptides such as substance P and calcitonin gene-related peptide. We summarize growing evidence that the role of corneal intraepithelial immune cells is likely different in corneal wound healing versus other inflammatory-dominated conditions. The role of different types of macrophages is also discussed, including how stromal macrophages with anti-inflammatory phenotypes communicate with corneal nerves to provide neuroprotection, while macrophages with pro-inflammatory phenotypes, along with other infiltrating cells including neutrophils and CD4+ T cells, can be inhibitory to corneal re-innervation. Finally, this review considers the bidirectional interactions between corneal immune cells and corneal nerves, and how leveraging this interaction could represent a potential therapeutic approach for corneal neuropathy.
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9
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Sensory nerves promote corneal inflammation resolution via CGRP mediated transformation of macrophages to the M2 phenotype through the PI3K/AKT signaling pathway. Int Immunopharmacol 2021; 102:108426. [PMID: 34906854 DOI: 10.1016/j.intimp.2021.108426] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/24/2021] [Accepted: 11/28/2021] [Indexed: 02/07/2023]
Abstract
OBJECTIVES To explore the role of the corneal sensory nerves in Pseudomonas aeruginosa (P. aeruginosa) keratitis, the synergistic effect between the sensory neurons and macrophages in calcitonin gene-related peptide (CGRP) release, and the functional mechanisms of CGRP-mediated transformation of macrophages to the M2 phenotype. METHODS Corneal nerve loss, macrophage recruitment, and CGRP expression were evaluated. To explore the synergistic effect between the sensory neurons and macrophages, RAW 264.7 cells were challenged with lipopolysaccharide (LPS), then trigeminal ganglion (TG) sensory neurons were isolated and co-incubated with macrophages, and CGRP expression was tested. To investigate the biological function of cornea neuron-initiated immune responses mediated by CGRP, BIBN 4096BS was used to inhibit CGRP in vivo and α-CGRP was used to simulate CGRP in vitro. The expressions of inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-10), M1 (CD80/CD86), M2 (CD163/CD206) macrophage markers, and signal transducers (PI3K/AKT) were detected. RESULTS P. aeruginosa infection induced corneal nerve loss, macrophage recruitment, and CGRP up-expression. CGRP was co-localized with macrophages. Co-culture showed that sensory neurons and macrophages can mediate CGRP release. More CGRP was released when the two types of cells were combined to respond to LPS. BIBN 4096BS promoted pro-inflammatory cytokines and inhibited the anti-inflammatory cytokines and signal transducers, while, α-CGRP inhibited the pro-inflammatory cytokines and M1 markers and promoted the anti-inflammatory cytokine, M2 markers, and signal transducers. CONCLUSIONS P. aeruginosa infection induces corneal sensory neuron activation, macrophage recruitment, and CGRP up-expression. The synergistic effect between the sensory neurons and macrophages promotes CGRP release. CGRP inhibits corneal inflammation and promotes the transformation of macrophages to the M2 phenotype through the PI3K/AKT signaling pathway.
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10
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Pham TL, Kakazu AH, He J, Nshimiyimana R, Petasis NA, Jun B, Bazan NG, Bazan HEP. Elucidating the structure and functions of Resolvin D6 isomers on nerve regeneration with a distinctive trigeminal transcriptome. FASEB J 2021; 35:e21775. [PMID: 34245621 PMCID: PMC8362171 DOI: 10.1096/fj.202100686r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 12/26/2022]
Abstract
Innervation sustains cornea integrity. Pigment epithelium‐derived factor (PEDF) plus docosahexaenoic acid (DHA) regenerated damaged nerves by stimulating the synthesis of a new stereoisomer of Resolvin D6 (RvD6si). Here, we resolved the structure of this lipid isolated from mouse tears after injured corneas were treated with PEDF + DHA. RvD6si synthesis was inhibited by fluvoxamine, a cytochrome P450 inhibitor, but not by 15‐ or 5‐LOX inhibitors, suggesting that the 4‐ and 17‐hydroxy of DHA have an RR‐ or SR‐configuration. The two compounds were chemically synthesized. Using chiral phase HPLC, four peaks of RvD6si1‐4 from tears were resolved. The RR‐RvD6 standard eluted as a single peak with RvD61 while pure SR‐RvD6 eluted with RvD63. The addition of these pure mediators prompted a trigeminal ganglion transcriptome response in injured corneas and showed that RR‐RvD6 was the more potent, increasing cornea sensitivity and nerve regeneration. RR‐RvD6 stimulates Rictor and hepatocyte growth factor (hgf) genes specifically as upstream regulators and a gene network involved in axon growth and suppression of neuropathic pain, indicating a novel function of this lipid mediator to maintain cornea integrity and homeostasis after injury.
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Affiliation(s)
- Thang L Pham
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, USA
| | - Azucena H Kakazu
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, USA
| | - Jiucheng He
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, USA
| | - Robert Nshimiyimana
- Department of Chemistry and Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, USA
| | - Nicos A Petasis
- Department of Chemistry and Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, USA
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, USA
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, USA
| | - Haydee E P Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, USA
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11
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Lasagni Vitar RM, Rama P, Ferrari G. The two-faced effects of nerves and neuropeptides in corneal diseases. Prog Retin Eye Res 2021; 86:100974. [PMID: 34098111 DOI: 10.1016/j.preteyeres.2021.100974] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 12/16/2022]
Abstract
Corneal nerves are instrumental to maintain cornea integrity through regulation of key physiological functions such as tear secretion, blink reflex, and neuropeptide turnover. Corneal nerve injury/stimulation can follow many insults including mechanical/chemical trauma, infections and surgeries. Nerve disruption initiates a process named neurogenic inflammation which leads to edema, pain, and recruitment and activation of leukocytes. Interestingly, leukocyte influx in the cornea can further damage nerves by releasing inflammatory mediators-including neuropeptides. The clinical outcome of neuroinflammation can be beneficial or detrimental to corneal integrity. On one side, it ensures prompt wound healing and prevents infections. On the other, prolonged and/or deranged neuroinflammation can permanently disrupt corneal integrity and impair vision. The cornea is an ideal site to study peripheral neuroinflammation and neurogenic inflammation since it receives the highest density of sensory nerves of the entire body. We will review the corneal nerve anatomy and neurochemistry, discuss the beneficial and detrimental effects of neurogenic inflammation in corneal wound healing, inflammatory processes, and pain. We will also examine the emerging remote impact of corneal nerve disruption on the trigeminal ganglion and the brain, highlighting the key role of neuropeptide Substance P. Finally, we will discuss the clinical relevance of such neuroinflammatory network in the context of severe and highly prevalent ocular diseases, including potential treatments.
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Affiliation(s)
- Romina Mayra Lasagni Vitar
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Paolo Rama
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Giulio Ferrari
- Cornea and Ocular Surface Disease Unit, Eye Repair Lab, IRCCS San Raffaele Scientific Institute, Milan, Italy.
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