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Mpakosi A, Kaliouli-Antonopoulou C. Immune Mechanisms of Filamentous Fungal Keratitis. Cureus 2024; 16:e61954. [PMID: 38855487 PMCID: PMC11162199 DOI: 10.7759/cureus.61954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2024] [Indexed: 06/11/2024] Open
Abstract
Filamentous fungal keratitis is a particularly serious eye infection that often results in ulceration, corneal perforation, and blindness. The cornea acts as a natural barrier against harmful agents due to the close connection of its epithelial cells. In addition, on its surface, there is a large number of substances with anti-inflammatory and bactericidal properties, such as secretory IgA and mucin glycoproteins, and antimicrobial peptides (AMPs), such as human β-defensin 2 (HBD-2) and LL-37, which are especially increased in filamentous fungal keratitis. The interaction between pathogenic fungi and the host's immune mechanisms is a complex process: pathogen-associated molecular pattern (PAMP) molecules (chitin, β-glucan, and mannan) found in the fungal cell wall are recognized by pattern recognition receptors (PRRs) (toll-like receptors {TLRs}, C-type lectin receptors {CLRs}, nucleotide-binding oligomerization domain-like receptors {NLRs}, and scavenger receptors {SR}) found in host defense cells, triggering the secretion of various types of cytokines, such as interleukins (IL), tumor necrosis factors (TNFs), and chemokines, which recruit macrophages and neutrophils to migrate to the site of infection and activate inflammatory responses. In addition, the interaction of hyphae and corneal epithelial cells can activate cluster of differentiation (CD) 4+ T cells, CD8+ T cells, and B cells and induce secretion of T-helper (Th)-type cytokines 2 (IL-4 and IL-13) and IgG.
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Affiliation(s)
- Alexandra Mpakosi
- Department of Microbiology, General Hospital of Nikaia "Agios Panteleimon", Piraeus, GRC
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Sepulveda-Beltran PA, Carletti P, Banda V, Mulpuri L, Levine H, Amescua G, Wang TP, Galor A, Tonk R. Infectious and Noninfectious Corneal Ulcers in Ocular Graft-Versus-Host Disease: Epidemiology, Clinical Characteristics, and Outcomes. Am J Ophthalmol 2024; 257:236-246. [PMID: 37774993 PMCID: PMC10842762 DOI: 10.1016/j.ajo.2023.09.018] [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: 06/01/2023] [Revised: 09/16/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023]
Abstract
PURPOSE To evaluate the incidence, clinical characteristics, microbiological profile, and therapeutic outcomes of corneal ulcers in individuals with chronic ocular graft-vs-host disease (coGVHD). DESIGN Retrospective clinical cohort study. METHODS Review of individuals diagnosed with coGVHD following hematopoietic stem cell transplantation (HSCT) who were seen at the Bascom Palmer Eye Institute between May 2010 and November 2021. Baseline demographics, clinical characteristics, microbiological profile, risk factors for corneal ulceration, and treatment outcomes were collected. Etiology was deemed infectious in individuals with a positive culture or appropriate clinical scenario (presence of stromal infiltrate or hypopyon); otherwise, ulcers were presumed to be noninfectious. Treatment success was defined as reepithelialization with infiltrate resolution, and treatment failure as progression to corneal perforation or keratoplasty. Kaplan-Meier survival analysis estimated the incidence of ulceration. Cox regression analyses examined demographic and risk factors. Infectious and noninfectious ulcer groups were compared using 2-way independent t tests, 1-way analysis of variances, and χ2 tests, as appropriate. RESULTS 173 individuals were included (53.7±14.4 years old; 59.0% male). Thirty-three individuals developed an ulcer 74.5±54.3 months after HSCT, with estimated 5- and 10-year incidences of 14% and 30%, respectively. Twenty-two (66.6%) ulcers were deemed infectious (15 microbiologically confirmed, 7 clinically) and 11 (33.3%) were deemed noninfectious. Risk factors for corneal ulceration included Black race (hazards ratio [HR] 2.89, 95% CI 1.30-6.42, P < .01), previous ocular surgery (HR 9.16, 95% CI 3.86-21.72, P < .01), eyelid margin abnormalities (HR 3.44, 95% CI 1.69-6.99, P < .01), and topical steroid use (HR 2.74, 95% CI 1.33-5.62, P < .01). Conversely, contact lens use reduced the risk of corneal ulceration (HR 0.29, 95% CI 0.13-0.66, P < .01). Infectious ulcers had a significantly higher frequency of treatment failure than noninfectious ulcers (57.1% vs 20.0%, P = .04). CONCLUSION Corneal ulceration is a potential complication of coGVHD, with several clinical features identified as risk factors. Infectious ulcers had worse outcomes than noninfectious ulcers.
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Affiliation(s)
- Paula A Sepulveda-Beltran
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Piero Carletti
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Victor Banda
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Lakshman Mulpuri
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Harry Levine
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Guillermo Amescua
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Trent P Wang
- Sylvester Comprehensive Cancer Center, Division of Transplantation and Cell Therapy, Department of Medicine (T.P.W.), University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Anat Galor
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.)
| | - Rahul Tonk
- From the Bascom Palmer Eye Institute, Department of Ophthalmology (P.A.S.-B., P.C., V.B., L.M., H.L., G.A., A.G., R.T.).
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Wang JS, Peng X, Zhao Z, Wang C, Xie HT, Zhang MC. Differential expression of antimicrobial peptides in human fungal keratitis. Int J Ophthalmol 2023; 16:1630-1635. [PMID: 37854369 PMCID: PMC10559020 DOI: 10.18240/ijo.2023.10.11] [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: 04/27/2023] [Accepted: 08/03/2023] [Indexed: 10/20/2023] Open
Abstract
AIM To analyze a series of antimicrobial peptides (AMPs) in corneal tissue from individuals with fungal keratitis (FK) during the active phase of the fungus infection and after healing. METHODS Patients undergone lamellar keratoplasty for the treatment of severe FK or corneal scar had their corneal buttons sampled. Quantitative real-time polymerase chain reaction (PCR) was used to ascertain the gene expression of human beta-defensin (HBD)-1, -2, -3, -9, S100A7, 8, 9, and LL-37. RESULTS All AMPs' messenger ribonucleic acid (mRNA) expression was considerably elevated in all samples (n=12). In contrast to controls, where HBD-2, -3, and S100A7 mRNAs were expressed at very low levels, it was discovered that HBD-1, -9, S100A8, S100A9, and LL-37 were constitutively expressed in all healed samples (n=4). HBD-1, -2 -3, S100A7, and LL-37 mRNAs were significantly increased in all active FK samples (n=8). The levels of HBD-9, S100A8, and S100A9 mRNAs were moderately upregulated in all active FK samples. Subgroup comparison showed that HBD-2 was significantly increased in Fusarium keratitis samples (n=5), and LL-37 mRNAs were significantly enhanced in Aspergillus keratitis samples (n=3). Whereas there was not significantly increased of HBD-1, -3, -9, S100A7, 8, 9 mRNA in Aspergillus keratitis samples compared with Fusarium keratitis samples. CONCLUSION AMPs expression is increased in active FK, but not all AMPs are equally expressed. HBD-2 and LL-37 expression levels are the highest, showing some specificity of AMP expression related to FK. Human AMPs, particularly HBD-2 may play a significant role in Fusarium keratitis and LL-37 might be the key player in Aspergillus keratitis.
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Affiliation(s)
- Jia-Song Wang
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
| | - Xi Peng
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
| | - Zhao Zhao
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
| | - Chao Wang
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
| | - Hua-Tao Xie
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
| | - Ming-Chang Zhang
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, Hubei Province, China
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Ouyang W, Wang S, Yan D, Wu J, Zhang Y, Li W, Hu J, Liu Z. The cGAS-STING pathway-dependent sensing of mitochondrial DNA mediates ocular surface inflammation. Signal Transduct Target Ther 2023; 8:371. [PMID: 37735446 PMCID: PMC10514335 DOI: 10.1038/s41392-023-01624-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 07/21/2023] [Accepted: 08/21/2023] [Indexed: 09/23/2023] Open
Abstract
The innate immune response is the main pathophysiological process of ocular surface diseases exposed to multiple environmental stresses. The epithelium is central to the innate immune response, but whether and how innate immunity is initiated by ocular epithelial cells in response to various environmental stresses in ocular surface diseases, such as dry eye, is still unclear. By utilizing two classic experimental dry eye models-a mouse ocular surface treated with benzalkonium chloride (BAC) and a mouse model with surgically removed extraorbital lachrymal glands, as well as dry eye patient samples-along with human corneal epithelial cells (HCE) exposed to hyperosmolarity, we have discovered a novel innate immune pathway in ocular surface epithelial cells. Under stress, mitochondrial DNA (mtDNA) was released into the cytoplasm through the mitochondrial permeability transition pore (mPTP) and further activated the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, aggravating downstream inflammatory responses and ocular surface damage. Genetic deletion or pharmacological suppression of STING and inhibition of mtDNA release reduced inflammatory responses, whereas mtDNA transfection supported cytoplasmic mtDNA-induced inflammatory responses by activating the cGAS-STING pathway. Our study clarified the cGAS-STING pathway-dependent sensing of mitochondrial DNA-mediated ocular surface inflammation, which elucidated a new mechanism of ocular surface diseases in response to multiple environmental stresses.
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Affiliation(s)
- Weijie Ouyang
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian, 361005, China
| | - Shoubi Wang
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China
- The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361005, China
| | - Dan Yan
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian, 361005, China
| | - Jieli Wu
- Changsha Aier Eye Hospital, Changsha, Hunan, 410016, China
| | - Yunuo Zhang
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian, 361005, China
| | - Wei Li
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian, 361005, China
| | - Jiaoyue Hu
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China.
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian, 361005, China.
| | - Zuguo Liu
- Xiamen University affiliated Xiamen Eye Center; Fujian Provincial Key Laboratory of Ophthalmology and Visual Science; Fujian Engineering and Research Center of Eye Regenerative Medicine; Eye Institute of Xiamen University; School of Medicine, Xiamen University, Xiamen, Fujian, 361005, China.
- Department of Ophthalmology, Xiang'an Hospital of Xiamen University, Xiamen, Fujian, 361005, China.
- Department of Ophthalmology, The First Affiliated Hospital of University of South China, Hengyang, Hunan, 421001, China.
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Yam GHF, Pi S, Du Y, Mehta JS. Posterior corneoscleral limbus: Architecture, stem cells, and clinical implications. Prog Retin Eye Res 2023; 96:101192. [PMID: 37392960 DOI: 10.1016/j.preteyeres.2023.101192] [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: 04/19/2023] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 07/03/2023]
Abstract
The limbus is a transition from the cornea to conjunctiva and sclera. In human eyes, this thin strip has a rich variation of tissue structures and composition, typifying a change from scleral irregularity and opacity to corneal regularity and transparency; a variation from richly vascularized conjunctiva and sclera to avascular cornea; the neural passage and drainage of aqueous humor. The limbal stroma is enriched with circular fibres running parallel to the corneal circumference, giving its unique role in absorbing small pressure changes to maintain corneal curvature and refractivity. It contains specific niches housing different types of stem cells for the corneal epithelium, stromal keratocytes, corneal endothelium, and trabecular meshwork. This truly reflects the important roles of the limbus in ocular physiology, and the limbal functionality is crucial for corneal health and the entire visual system. Since the anterior limbus containing epithelial structures and limbal epithelial stem cells has been extensively reviewed, this article is focused on the posterior limbus. We have discussed the structural organization and cellular components of the region beneath the limbal epithelium, the characteristics of stem cell types: namely corneal stromal stem cells, endothelial progenitors and trabecular meshwork stem cells, and recent advances leading to the emergence of potential cell therapy options to replenish their respective mature cell types and to correct defects causing corneal abnormalities. We have reviewed different clinical disorders associated with defects of the posterior limbus and summarized the available preclinical and clinical evidence about the developing topic of cell-based therapy for corneal disorders.
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Affiliation(s)
- Gary Hin-Fai Yam
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore; McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.
| | - Shaohua Pi
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yiqin Du
- Department of Ophthalmology, University of South Florida, Tampa, FL, USA
| | - Jodhbir S Mehta
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore; Department of Cornea and External Eye Disease, Singapore National Eye Centre, Singapore; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore (NUS) Medical School, Singapore.
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Sun YC, Hung KF, Li TY, Chang YA, Yeh PT, Hu FR. Transmembrane Mucin 1 Blocks Fluorescein Ingress to Corneal Epithelium. Invest Ophthalmol Vis Sci 2022; 63:31. [PMID: 35212722 PMCID: PMC8883176 DOI: 10.1167/iovs.63.2.31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Purpose To determine the role of transmembrane mucins in blocking fluorescein ingress to the corneal epithelium and its deficiency in contributing to corneal fluorescein punctate staining. Methods A dry eye model was established by extirpating lacrimal and Harderian glands in rabbits to correlate the expression of mucins with fluorescein-stained areas on the corneal button using immunofluorescence. Expression of transmembrane mucins was promoted in human corneal epithelial cells (HCECs) by culturing with the mucin-promoting medium (MPM) or diquafosol treatment. Conversely, the expression of mucins was downregulated by knockdown with short hairpin RNA. The role of mucin1 extracellular domain in fluorescein ingress was further verified by overexpression of N-terminally truncated mucin1 in HCECs. Results In the rabbit dry eye model, the expression level of mucin1 was significantly decreased in superficial corneal epithelial cells where fluorescein punctate staining was observed. Upregulation of mucin1 and mucin16 in HCECs promoted by MPM or by diquafosol treatment impeded intracellular fluorescein ingress. Downregulation of mucin1 and mucin16 enhanced fluorescence ingress in HCECs after fluorescein staining. Overexpression of truncated mucin1 did not alter the fluorescein intensity of fluorescein-stained HCECs, supporting the notion that the ability of mucin1 to block fluorescein ingress was primarily mediated by its extracellular domain. Minimal inherent expression of mucin16 in the rabbit cornea limited the validation of its role in blocking fluorescein ingress in vivo. Conclusion Transmembrane mucin1 blocks fluorescein ingress in the corneal epithelium, explaining how fluorescein staining is positive when the level of transmembrane mucins is disturbed in dry eyes.
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Affiliation(s)
- Yi-Chen Sun
- Department of Ophthalmology, Taipei Tzu Chi Hospital, The Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan.,College of Medicine, Tzu-Chi University, Hualien, Taiwan
| | - Kai-Feng Hung
- Department of Medical Research, Division of Translational Research, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.,Department of Dentistry, School of Dentistry, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
| | - Tzu-Yun Li
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-An Chang
- Graduate Institute of Veterinary Clinical Science, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Ting Yeh
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Fung-Rong Hu
- Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
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Histatin-1 Attenuates LPS-Induced Inflammatory Signaling in RAW264.7 Macrophages. Int J Mol Sci 2021; 22:ijms22157856. [PMID: 34360629 PMCID: PMC8345949 DOI: 10.3390/ijms22157856] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 12/20/2022] Open
Abstract
Macrophages play a critical role in the inflammatory response to environmental triggers, such as lipopolysaccharide (LPS). Inflammatory signaling through macrophages and the innate immune system are increasingly recognized as important contributors to multiple acute and chronic disease processes. Nitric oxide (NO) is a free radical that plays an important role in immune and inflammatory responses as an important intercellular messenger. In addition, NO has an important role in inflammatory responses in mucosal environments such as the ocular surface. Histatin peptides are well-established antimicrobial and wound healing agents. These peptides are important in multiple biological systems, playing roles in responses to the environment and immunomodulation. Given the importance of macrophages in responses to environmental triggers and pathogens, we investigated the effect of histatin-1 (Hst1) on LPS-induced inflammatory responses and the underlying molecular mechanisms in RAW264.7 (RAW) macrophages. LPS-induced inflammatory signaling, NO production and cytokine production in macrophages were tested in response to treatment with Hst1. Hst1 application significantly reduced LPS-induced NO production, inflammatory cytokine production, and inflammatory signaling through the JNK and NF-kB pathways in RAW cells. These results demonstrate that Hst1 can inhibit LPS-induced inflammatory mediator production and MAPK signaling pathways in macrophages.
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