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Hou XW, Wang Y, Wu Q, Ke C, Pan CW. A review of study designs and data analyses in metabolomics studies in myopia. Anal Biochem 2022; 655:114850. [PMID: 35970413 DOI: 10.1016/j.ab.2022.114850] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/15/2022] [Accepted: 08/03/2022] [Indexed: 11/25/2022]
Abstract
Metabolomics analyzes the entire range of small molecule metabolites in biological systems to reveal the response signals that are transmitted from "genetics and environment", which could help us understand complex phenotypes of diseases. Metabolomics has been successfully applied to the study of eye diseases including age-related macular degeneration, glaucoma, and diabetic retinopathy. In this review, we summarize the findings of myopic metabolomics and discuss them from a design and analysis perspective. Finally, we provide new ideas for the future development of myopia metabolomics research based on the broader ocular metabolomics study.
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Affiliation(s)
- Xiao-Wen Hou
- School of Public Health, Medical College of Soochow University, Suzhou, China
| | - Ying Wang
- School of Public Health, Medical College of Soochow University, Suzhou, China
| | - Qian Wu
- School of Public Health, Medical College of Soochow University, Suzhou, China
| | - Chaofu Ke
- School of Public Health, Medical College of Soochow University, Suzhou, China
| | - Chen-Wei Pan
- School of Public Health, Medical College of Soochow University, Suzhou, China.
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2
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Teissier T, Boulanger E, Cox LS. Interconnections between Inflammageing and Immunosenescence during Ageing. Cells 2022; 11:359. [PMID: 35159168 PMCID: PMC8834134 DOI: 10.3390/cells11030359] [Citation(s) in RCA: 71] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 01/13/2022] [Accepted: 01/15/2022] [Indexed: 02/04/2023] Open
Abstract
Acute inflammation is a physiological response to injury or infection, with a cascade of steps that ultimately lead to the recruitment of immune cells to clear invading pathogens and heal wounds. However, chronic inflammation arising from the continued presence of the initial trigger, or the dysfunction of signalling and/or effector pathways, is harmful to health. While successful ageing in older adults, including centenarians, is associated with low levels of inflammation, elevated inflammation increases the risk of poor health and death. Hence inflammation has been described as one of seven pillars of ageing. Age-associated sterile, chronic, and low-grade inflammation is commonly termed inflammageing-it is not simply a consequence of increasing chronological age, but is also a marker of biological ageing, multimorbidity, and mortality risk. While inflammageing was initially thought to be caused by "continuous antigenic load and stress", reports from the last two decades describe a much more complex phenomenon also involving cellular senescence and the ageing of the immune system. In this review, we explore some of the main sources and consequences of inflammageing in the context of immunosenescence and highlight potential interventions. In particular, we assess the contribution of cellular senescence to age-associated inflammation, identify patterns of pro- and anti-inflammatory markers characteristic of inflammageing, describe alterations in the ageing immune system that lead to elevated inflammation, and finally assess the ways that diet, exercise, and pharmacological interventions can reduce inflammageing and thus, improve later life health.
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Affiliation(s)
- Thibault Teissier
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;
| | - Eric Boulanger
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167—RID-AGE—Facteurs de Risque et Déterminants Moléculaires des Maladies Liées au Vieillissement, F-59000 Lille, France;
| | - Lynne S. Cox
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;
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3
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Wan SJ, Datta A, Flandrin O, Metruccio MME, Ma S, Nieto V, Kroken AR, Hill RZ, Bautista DM, Evans DJ, Fleiszig SMJ. Nerve-associated transient receptor potential ion channels can contribute to intrinsic resistance to bacterial adhesion in vivo. FASEB J 2021; 35:e21899. [PMID: 34569661 DOI: 10.1096/fj.202100874r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/05/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022]
Abstract
The cornea of the eye differs from other mucosal surfaces in that it lacks a viable bacterial microbiome and by its unusually high density of sensory nerve endings. Here, we explored the role of corneal nerves in preventing bacterial adhesion. Pharmacological and genetic methods were used to inhibit the function of corneal sensory nerves or their associated transient receptor potential cation channels TRPA1 and TRPV1. Impacts on bacterial adhesion, resident immune cells, and epithelial integrity were examined using fluorescent labeling and quantitative confocal imaging. TRPA1/TRPV1 double gene-knockout mice were more susceptible to adhesion of environmental bacteria and to that of deliberately-inoculated Pseudomonas aeruginosa. Supporting the involvement of TRPA1/TRPV1-expressing corneal nerves, P. aeruginosa adhesion was also promoted by treatment with bupivacaine, or ablation of TRPA1/TRPV1-expressing nerves using RTX. Moreover, TRPA1/TRPV1-dependent defense was abolished by enucleation which severs corneal nerves. High-resolution imaging showed normal corneal ultrastructure and surface-labeling by wheat-germ agglutinin for TRPA1/TRPV1 knockout murine corneas, and intact barrier function by absence of fluorescein staining. P. aeruginosa adhering to corneas after perturbation of nerve or TRPA1/TRPV1 function failed to penetrate the surface. Single gene-knockout mice showed roles for both TRPA1 and TRPV1, with TRPA1-/- more susceptible to P. aeruginosa adhesion while TRPV1-/- corneas instead accumulated environmental bacteria. Corneal CD45+/CD11c+ cell responses to P. aeruginosa challenge, previously shown to counter bacterial adhesion, also depended on TRPA1/TRPV1 and sensory nerves. Together, these results demonstrate roles for corneal nerves and TRPA1/TRPV1 in corneal resistance to bacterial adhesion in vivo and suggest that the mechanisms involve resident immune cell populations.
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Affiliation(s)
- Stephanie J Wan
- Vision Science Program, University of California, Berkeley, California, USA
| | - Ananya Datta
- School of Optometry, University of California, Berkeley, California, USA
| | - Orneika Flandrin
- Vision Science Program, University of California, Berkeley, California, USA
| | | | - Sophia Ma
- School of Optometry, University of California, Berkeley, California, USA
| | - Vincent Nieto
- School of Optometry, University of California, Berkeley, California, USA
| | - Abby R Kroken
- School of Optometry, University of California, Berkeley, California, USA
| | - Rose Z Hill
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - Diana M Bautista
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, California, USA.,College of Pharmacy, Touro University California, Vallejo, California, USA
| | - Suzanne M J Fleiszig
- Vision Science Program, University of California, Berkeley, California, USA.,School of Optometry, University of California, Berkeley, California, USA.,Graduate Groups in Microbiology and Infectious Diseases & Immunity, University of California, Berkeley, California, USA
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4
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Ung L, Chodosh J. Foundational concepts in the biology of bacterial keratitis. Exp Eye Res 2021; 209:108647. [PMID: 34097906 PMCID: PMC8595513 DOI: 10.1016/j.exer.2021.108647] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/28/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022]
Abstract
Bacterial infections of the cornea, or bacterial keratitis (BK), are notorious for causing rapidly fulminant disease and permanent vision loss, even among treated patients. In the last sixty years, dramatic upward trajectories in the frequency of BK have been observed internationally, driven in large part by the commercialization of hydrogel contact lenses in the late 1960s. Despite this worsening burden of disease, current evidence-based therapies for BK - including broad-spectrum topical antibiotics and, if indicated, topical corticosteroids - fail to salvage vision in a substantial proportion of affected patients. Amid growing concerns of rapidly diminishing antibiotic utility, there has been renewed interest in urgently needed novel treatments that may improve clinical outcomes on an individual and public health level. Bridging the translational gap in the care of BK requires the identification of new therapeutic targets and rational treatment design, but neither of these aims can be achieved without understanding the complex biological processes that determine how bacterial corneal infections arise, progress, and resolve. In this chapter, we synthesize the current wealth of human and animal experimental data that now inform our understanding of basic BK pathophysiology, in context with modern concepts in ocular immunology and microbiology. By identifying the key molecular determinants of clinical disease, we explore how novel treatments can be developed and translated into routine patient care.
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Affiliation(s)
- Lawson Ung
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Infectious Disease Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - James Chodosh
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Infectious Disease Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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5
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Ke R, Zhang M, Zhou Q, Yang Y, Shen R, Huang H, Zhang X. Bacteriological profiles and drug susceptibility of Streptococcus isolated from conjunctival sac of healthy children. BMC Pediatr 2020; 20:306. [PMID: 32571257 PMCID: PMC7310448 DOI: 10.1186/s12887-020-02203-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 06/12/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To investigate bacterial flora and antibiotics susceptibility of Streptococcus pneumoniae isolated from the conjunctival sac of heathy children. METHODS Bacteria were isolated from the secretions of conjunctival sac of healthy children between 2015 and 2018. Antimicrobial susceptibility of isolated S. pneumoniae strains were determined using microbroth dilution method. RESULTS The sac secretions were collected from a total of 6440 children. 1409 samples presented bacterial growth, accounting for 21.8% of the samples. Among the 22 bacterial species isolated, 528 samples presented Gram-positive Staphylococcus spp. growth, accounting for 37.4% of the isolates, followed by Corynebacterium spp., counting for 30% of the isolates and Streptococcus pneumoniae, counting for 21.4% of the isolates. Antibiotics susceptibility tests showed that the majority of S. pneumoniae isolates were sensitive to most antibiotics tested. However, 72.8 and 81.2% of the isolates were resistant to erythromycin and tetracycline, respectively, and over 10% of them were resistant to gentamicin, tobramycin and rifampicin. CONCLUSIONS The bacterial flora of healthy children is mainly consisted of Gram-positive bacteria belonging to Corynebacterium spp. and Streptococcus spp.; most of S. pneumoniae isolates were sensitive to antibiotics except erythromycin and tetracycline.
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Affiliation(s)
- Ruili Ke
- Department of Ophthalmology, The People's Hospital of Longhua, 38 Jianshe East Road, Shenzhen, 518000, China
| | - Min Zhang
- Research Institute of Shenzhen Children's Hospital, Shenzhen, China
| | - Qin Zhou
- Department of Ophthalmology, The People's Hospital of Longhua, 38 Jianshe East Road, Shenzhen, 518000, China
| | - Yunfei Yang
- Department of Ophthalmology, The People's Hospital of Longhua, 38 Jianshe East Road, Shenzhen, 518000, China
| | - Ruifen Shen
- Department of Ophthalmology, The People's Hospital of Longhua, 38 Jianshe East Road, Shenzhen, 518000, China
| | - Huipin Huang
- Department of Ophthalmology, The People's Hospital of Longhua, 38 Jianshe East Road, Shenzhen, 518000, China
| | - Xiangrong Zhang
- Department of Ophthalmology, The People's Hospital of Longhua, 38 Jianshe East Road, Shenzhen, 518000, China.
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Fleiszig SMJ, Kroken AR, Nieto V, Grosser MR, Wan SJ, Metruccio MME, Evans DJ. Contact lens-related corneal infection: Intrinsic resistance and its compromise. Prog Retin Eye Res 2019; 76:100804. [PMID: 31756497 DOI: 10.1016/j.preteyeres.2019.100804] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 11/05/2019] [Accepted: 11/12/2019] [Indexed: 12/20/2022]
Abstract
Contact lenses represent a widely utilized form of vision correction with more than 140 million wearers worldwide. Although generally well-tolerated, contact lenses can cause corneal infection (microbial keratitis), with an approximate annualized incidence ranging from ~2 to ~20 cases per 10,000 wearers, and sometimes resulting in permanent vision loss. Research suggests that the pathogenesis of contact lens-associated microbial keratitis is complex and multifactorial, likely requiring multiple conspiring factors that compromise the intrinsic resistance of a healthy cornea to infection. Here, we outline our perspective of the mechanisms by which contact lens wear sometimes renders the cornea susceptible to infection, focusing primarily on our own research efforts during the past three decades. This has included studies of host factors underlying the constitutive barrier function of the healthy cornea, its response to bacterial challenge when intrinsic resistance is not compromised, pathogen virulence mechanisms, and the effects of contact lens wear that alter the outcome of host-microbe interactions. For almost all of this work, we have utilized the bacterium Pseudomonas aeruginosa because it is the leading cause of lens-related microbial keratitis. While not yet common among corneal isolates, clinical isolates of P. aeruginosa have emerged that are resistant to virtually all currently available antibiotics, leading the United States CDC (Centers for Disease Control) to add P. aeruginosa to its list of most serious threats. Compounding this concern, the development of advanced contact lenses for biosensing and augmented reality, together with the escalating incidence of myopia, could portent an epidemic of vision-threatening corneal infections in the future. Thankfully, technological advances in genomics, proteomics, metabolomics and imaging combined with emerging models of contact lens-associated P. aeruginosa infection hold promise for solving the problem - and possibly life-threatening infections impacting other tissues.
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Affiliation(s)
- Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, CA, USA; Graduate Group in Vision Science, University of California, Berkeley, CA, USA; Graduate Groups in Microbiology and Infectious Diseases & Immunity, University of California, Berkeley, CA, USA.
| | - Abby R Kroken
- School of Optometry, University of California, Berkeley, CA, USA
| | - Vincent Nieto
- School of Optometry, University of California, Berkeley, CA, USA
| | | | - Stephanie J Wan
- Graduate Group in Vision Science, University of California, Berkeley, CA, USA
| | | | - David J Evans
- School of Optometry, University of California, Berkeley, CA, USA; College of Pharmacy, Touro University California, Vallejo, CA, USA
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Xu S, Hazlett LD. MicroRNAs in Ocular Infection. Microorganisms 2019; 7:microorganisms7090359. [PMID: 31533211 PMCID: PMC6780979 DOI: 10.3390/microorganisms7090359] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/13/2019] [Accepted: 09/16/2019] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) are small, non-coding, regulatory RNA molecules and constitute a newly recognized, important layer of gene-expression regulation at post-transcriptional levels. miRNAs quantitatively fine tune the expression of their downstream genes in a cell type- and developmental stage-specific fashion. miRNAs have been proven to play important roles in the normal development and function as well as in the pathogenesis of diseases in all tissues and organ systems. miRNAs have emerged as new therapeutic targets and biomarkers for treatment and diagnosis of various diseases. Although miRNA research in ocular infection remains in its early stages, a handful of pioneering studies have provided insight into the roles of miRNAs in the pathogenesis of parasitic, fungal, bacterial, and viral ocular infections. Here, we review the current status of research in miRNAs in several major ocular infectious diseases. We predict that the field of miRNAs in ocular infection will greatly expand with the discovery of novel miRNA-involved molecular mechanisms that will inform development of new therapies and identify novel diagnostic biomarkers.
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Affiliation(s)
- Shunbin Xu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
| | - Linda D Hazlett
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
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Wu YT, Truong TN, Tam C, Mendoza MN, Zhu L, Evans DJ, Fleiszig SMJ. Impact of topical corticosteroid pretreatment on susceptibility of the injured murine cornea to Pseudomonas aeruginosa colonization and infection. Exp Eye Res 2018; 179:1-7. [PMID: 30343040 DOI: 10.1016/j.exer.2018.10.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/04/2018] [Accepted: 10/17/2018] [Indexed: 10/28/2022]
Abstract
Research with animal models of Pseudomonas aeruginosa keratitis has shown that use of a topical corticosteroid alone against an established infection can significantly increase the number of colonizing bacteria or worsen clinical disease. Moreover, retrospective analysis has suggested that corticosteroid use in humans is associated with an increased risk of keratitis in eyes with pre-existing disease. Thus, while corticosteroids are often used to reduce ocular inflammation in the absence of infection, the risk of opportunistic infection remains a concern. However, the effect of corticosteroids on the intrinsic barrier function of uninfected corneas is unknown. Here, we tested if short-term topical corticosteroid treatment of an uninfected murine cornea would increase susceptibility to P. aeruginosa colonization or infection after epithelial injury. Topical prednisolone acetate (1%) was administered to one eye of C57BL/6 mice three times a day for 3 days; control eyes were treated with sterile PBS. Prior to inoculation with a cytotoxic P. aeruginosa corneal isolate strain 6206, corneas were subject to superficial-injury by tissue paper blotting, or scratch-injured followed by 12 h of healing. Previously we have shown that blotting renders mouse corneas susceptible to P. aeruginosa adhesion, but not infection, while 12 h healing reduces susceptibility to infection after scratching. Corneas were evaluated at 48 h for bacterial colonization and microbial keratitis (MK). To monitor impact on wound healing, corneal integrity was examined by fluorescein staining immediately after scarification and after 12 h healing. For both the tissue paper blotting and scratch-injury models, there was no significant difference in P. aeruginosa colonization at 48 h between corticosteroid-pretreated eyes and controls. With the blotting model, one case of MK was observed in a control (PBS-pretreated) cornea; none in corticosteroid-pretreated corneas. With the 12 h healing model, MK occurred in 6 of 17 corticosteroid-pretreated eyes versus 2 of 17 controls, a difference not statistically significant. Corticosteroid-pretreated eyes showed greater fluorescein staining 12 h after scarification injury, but this did not coincide with increased colonization or MK. Together, these data show that short-term topical corticosteroid therapy on an uninfected murine cornea does not necessarily enhance its susceptibility to P. aeruginosa colonization or infection after injury, even when it induces fluorescein staining.
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Affiliation(s)
- Yvonne T Wu
- School of Optometry, University of California, Berkeley, CA, USA
| | - Tan N Truong
- School of Optometry, University of California, Berkeley, CA, USA; Vision Science Program, University of California, Berkeley, CA, USA
| | - Connie Tam
- School of Optometry, University of California, Berkeley, CA, USA
| | - Myra N Mendoza
- School of Optometry, University of California, Berkeley, CA, USA
| | - Lucia Zhu
- School of Optometry, University of California, Berkeley, CA, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, CA, USA; College of Pharmacy, Touro University California, Vallejo, CA, USA
| | - Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, CA, USA; Vision Science Program, University of California, Berkeley, CA, USA; Graduate Groups in Microbiology, And Infectious Diseases & Immunity, University of California, Berkeley, CA, USA.
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9
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Wan SJ, Sullivan AB, Shieh P, Metruccio MME, Evans DJ, Bertozzi CR, Fleiszig SMJ. IL-1R and MyD88 Contribute to the Absence of a Bacterial Microbiome on the Healthy Murine Cornea. Front Microbiol 2018; 9:1117. [PMID: 29896179 PMCID: PMC5986933 DOI: 10.3389/fmicb.2018.01117] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 05/11/2018] [Indexed: 01/09/2023] Open
Abstract
Microbial communities are important for the health of mucosal tissues. Traditional culture and gene sequencing have demonstrated bacterial populations on the conjunctiva. However, it remains unclear if the cornea, a transparent tissue critical for vision, also hosts a microbiome. Corneas of wild-type, IL-1R (-/-) and MyD88 (-/-) C57BL/6 mice were imaged after labeling with alkyne-functionalized D-alanine (alkDala), a probe that only incorporates into the peptidoglycan of metabolically active bacteria. Fluorescence in situ hybridization (FISH) was also used to detect viable bacteria. AlkDala labeling was rarely observed on healthy corneas. In contrast, adjacent conjunctivae harbored filamentous alkDala-positive forms, that also labeled with DMN-Tre, a Corynebacterineae-specific probe. FISH confirmed the absence of viable bacteria on healthy corneas, which also cleared deliberately inoculated bacteria within 24 h. Differing from wild-type, both IL-1R (-/-) and MyD88 (-/-) corneas harbored numerous alkDala-labeled bacteria, a result abrogated by topical antibiotics. IL-1R (-/-) corneas were impermeable to fluorescein suggesting that bacterial colonization did not reflect decreased epithelial integrity. Thus, in contrast to the conjunctiva and other mucosal surfaces, healthy murine corneas host very few viable bacteria, and this constitutive state requires the IL-1R and MyD88. While this study cannot exclude the presence of fungi, viruses, or non-viable or dormant bacteria, the data suggest that healthy murine corneas do not host a resident viable bacterial community, or microbiome, the absence of which could have important implications for understanding the homeostasis of this tissue.
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Affiliation(s)
- Stephanie J Wan
- Vision Science Program, University of California, Berkeley, Berkeley, CA, United States
| | - Aaron B Sullivan
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States
| | - Peyton Shieh
- College of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Matteo M E Metruccio
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States
| | - David J Evans
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States
- College of Pharmacy, Touro University California, Vallejo, CA, United States
| | - Carolyn R Bertozzi
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States
- Graduate Groups in Vision Sciences, Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, Berkeley, CA, United States
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10
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Foulsham W, Coco G, Amouzegar A, Chauhan SK, Dana R. When Clarity Is Crucial: Regulating Ocular Surface Immunity. Trends Immunol 2018; 39:288-301. [PMID: 29248310 PMCID: PMC5880704 DOI: 10.1016/j.it.2017.11.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/28/2017] [Accepted: 11/29/2017] [Indexed: 12/23/2022]
Abstract
The ocular surface is a unique mucosal immune compartment in which anatomical, physiological, and immunological features act in concert to foster a particularly tolerant microenvironment. These mechanisms are vital to the functional competence of the eye, a fact underscored by the devastating toll of excessive inflammation at the cornea - blindness. Recent data have elucidated the contributions of specific anatomical components, immune cells, and soluble immunoregulatory factors in promoting homeostasis at the ocular surface. We highlight research trends at this distinctive mucosal barrier and identify crucial gaps in our current knowledge.
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Affiliation(s)
- William Foulsham
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA; University College London (UCL) Institute of Ophthalmology, University College London, London, UK
| | - Giulia Coco
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Afsaneh Amouzegar
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Sunil K Chauhan
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
| | - Reza Dana
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
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11
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Metruccio MME, Tam C, Evans DJ, Xie AL, Stern ME, Fleiszig SMJ. Contributions of MyD88-dependent receptors and CD11c-positive cells to corneal epithelial barrier function against Pseudomonas aeruginosa. Sci Rep 2017; 7:13829. [PMID: 29062042 PMCID: PMC5653778 DOI: 10.1038/s41598-017-14243-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/06/2017] [Indexed: 12/19/2022] Open
Abstract
Previously we reported that corneal epithelial barrier function against Pseudomonas aeruginosa was MyD88-dependent. Here, we explored contributions of MyD88-dependent receptors using vital mouse eyes and confocal imaging. Uninjured IL-1R (−/−) or TLR4 (−/−) corneas, but not TLR2 (−/−), TLR5 (−/−), TLR7 (−/−), or TLR9 (−/−), were more susceptible to P. aeruginosa adhesion than wild-type (3.8-fold, 3.6-fold respectively). Bacteria adherent to the corneas of IL-1R (−/−) or TLR5 (−/−) mice penetrated beyond the epithelial surface only if the cornea was superficially-injured. Bone marrow chimeras showed that bone marrow-derived cells contributed to IL-1R-dependent barrier function. In vivo, but not ex vivo, stromal CD11c+ cells responded to bacterial challenge even when corneas were uninjured. These cells extended processes toward the epithelial surface, and co-localized with adherent bacteria in superficially-injured corneas. While CD11c+ cell depletion reduced IL-6, IL-1β, CXCL1, CXCL2 and CXCL10 transcriptional responses to bacteria, and increased susceptibility to bacterial adhesion (>3-fold), the epithelium remained resistant to bacterial penetration. IL-1R (−/−) corneas also showed down-regulation of IL-6 and CXCL1 genes with and without bacterial challenge. These data show complex roles for TLR4, TLR5, IL-1R and CD11c+ cells in constitutive epithelial barrier function against P. aeruginosa, with details dependent upon in vivo conditions.
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Affiliation(s)
| | - Connie Tam
- School of Optometry, University of California, Berkeley, CA, 94720, USA.,Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, CA, 94720, USA.,College of Pharmacy, Touro University California, Vallejo, CA, 94592, USA
| | - Anna L Xie
- School of Optometry, University of California, Berkeley, CA, 94720, USA
| | | | - Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, CA, 94720, USA. .,Graduate Groups in Vision Science, Microbiology, and Infectious Diseases & Immunity, University of California, Berkeley, CA, 94720, USA.
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12
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Mucosal fluid glycoprotein DMBT1 suppresses twitching motility and virulence of the opportunistic pathogen Pseudomonas aeruginosa. PLoS Pathog 2017; 13:e1006392. [PMID: 28489917 PMCID: PMC5440049 DOI: 10.1371/journal.ppat.1006392] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/22/2017] [Accepted: 04/28/2017] [Indexed: 12/22/2022] Open
Abstract
It is generally thought that mucosal fluids protect underlying epithelial surfaces against opportunistic infection via their antimicrobial activity. However, our published data show that human tear fluid can protect against the major opportunistic pathogen Pseudomonas aeruginosa independently of bacteriostatic activity. Here, we explored the mechanisms for tear protection, focusing on impacts of tear fluid on bacterial virulence factor expression. Results showed that tear fluid suppressed twitching motility, a type of surface-associated movement conferred by pili. Previously, we showed that twitching is critical for P. aeruginosa traversal of corneal epithelia, exit from epithelial cells after internalization, and corneal virulence. Inhibition of twitching by tear fluid was dose-dependent with dilutions to 6.25% retaining activity. Purified lactoferrin, lysozyme, and contrived tears containing these, and many other, tear components lacked the activity. Systematic protein fractionation, mass spectrometry, and immunoprecipitation identified the glycoprotein DMBT1 (Deleted in Malignant Brain Tumors 1) in tear fluid as required. DMBT1 purified from human saliva also inhibited twitching, as well as P. aeruginosa traversal of human corneal epithelial cells in vitro, and reduced disease pathology in a murine model of corneal infection. DMBT1 did not affect PilA expression, nor bacterial intracellular cyclicAMP levels, and suppressed twitching motility of P. aeruginosa chemotaxis mutants (chpB, pilK), and an adenylate cyclase mutant (cyaB). However, dot-immunoblot assays showed purified DMBT1 binding of pili extracted from PAO1 suggesting that twitching inhibition may involve a direct interaction with pili. The latter could affect extension or retraction of pili, their interactions with biotic or abiotic surfaces, or cause their aggregation. Together, the data suggest that DMBT1 inhibition of twitching motility contributes to the mechanisms by which mucosal fluids protect against P. aeruginosa infection. This study also advances our understanding of how mucosal fluids protect against infection, and suggests directions for novel biocompatible strategies to protect our surface epithelia against a major opportunistic pathogen.
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Jolly AL, Agarwal P, Metruccio MME, Spiciarich DR, Evans DJ, Bertozzi CR, Fleiszig SMJ. Corneal surface glycosylation is modulated by IL-1R and Pseudomonas aeruginosa challenge but is insufficient for inhibiting bacterial binding. FASEB J 2017; 31:2393-2404. [PMID: 28223334 DOI: 10.1096/fj.201601198r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/30/2017] [Indexed: 11/11/2022]
Abstract
Cell surface glycosylation is thought to be involved in barrier function against microbes at mucosal surfaces. Previously we showed that the epithelium of healthy mouse corneas becomes vulnerable to Pseudomonas aeruginosa adhesion if it lacks the innate defense protein MyD88 (myeloid differentiation primary response gene 88), or after superficial injury by blotting with tissue paper. Here we explored their effect on corneal surface glycosylation using a metabolic label, tetra-acetylated N-azidoacetylgalactosamine (Ac4GalNAz). Ac4GalNAz treatment labeled the surface of healthy mouse corneas, leaving most cells viable, and bacteria preferentially associated with GalNAz-labeled regions. Surprisingly, corneas from MyD88-/- mice displayed similar GalNAz labeling to wild-type corneas, but labeling was reduced and patchy on IL-1 receptor (IL-1R)-knockout mouse corneas (P < 0.05, ANOVA). Tissue paper blotting removed GalNAz-labeled surface cells, causing DAPI labeling (permeabilization) of underlying cells. MS of material collected on the tissue paper blots revealed 67 GalNAz-labeled proteins, including intracellular proteins. These data show that the normal distribution of surface glycosylation requires IL-1R, but not MyD88, and is not sufficient to prevent bacterial binding. They also suggest increased P. aeruginosa adhesion to MyD88-/- and blotted corneas is not due to reduction in total surface glycosylation, and for tissue paper blotting is likely due to cell permeabilization.-Jolly, A. L., Agarwal, P., Metruccio, M. M. E., Spiciarich, D. R., Evans, D. J., Bertozzi, C. R., Fleiszig, S. M. J. Corneal surface glycosylation is modulated by IL-1R and Pseudomonas aeruginosa challenge but is insufficient for inhibiting bacterial binding.
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Affiliation(s)
- Amber L Jolly
- School of Optometry, University of California, Berkeley, Berkeley, California, USA
| | - Paresh Agarwal
- College of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - Matteo M E Metruccio
- School of Optometry, University of California, Berkeley, Berkeley, California, USA
| | - David R Spiciarich
- College of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - David J Evans
- School of Optometry, University of California, Berkeley, Berkeley, California, USA.,College of Pharmacy, Touro University California, Vallejo, California, USA
| | - Carolyn R Bertozzi
- College of Chemistry, University of California, Berkeley, Berkeley, California, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, USA
| | - Suzanne M J Fleiszig
- School of Optometry, University of California, Berkeley, Berkeley, California, USA; .,Graduate Division of Vision Sciences, University of California, Berkeley, Berkeley, California, USA.,Graduate Division of Microbiology, University of California, Berkeley, Berkeley, California, USA.,Graduate Division of Infectious Diseases and Immunity, University of California, Berkeley, Berkeley, California, USA
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Galletti JG, Guzmán M, Giordano MN. Mucosal immune tolerance at the ocular surface in health and disease. Immunology 2017; 150:397-407. [PMID: 28108991 DOI: 10.1111/imm.12716] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/28/2016] [Accepted: 01/12/2017] [Indexed: 12/15/2022] Open
Abstract
The ocular surface is constantly exposed to environmental irritants, allergens and pathogens, against which it can mount a prompt immune response to preserve its integrity. But to avoid unnecessary inflammation, the ocular surface's mucosal immune system must also discriminate between harmless and potentially dangerous antigens, a seemingly complicated task. Despite its unique features, the ocular surface is a mucosal lining, and as such, it shares some homeostatic and pathophysiological mechanisms with other mucosal surfaces. The purpose of this review is to explore the mucosal homeostatic immune function of the ocular surface in both the healthy and diseased states, with a special focus on mucosal immunology concepts. The information discussed in this review has been retrieved by PubMed searches for literature published from January 1981 to October 2016.
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Affiliation(s)
- Jeremías G Galletti
- Immunology Laboratory, Institute of Experimental Medicine, National Academy of Medicine/CONICET, Buenos Aires, Argentina
| | - Mauricio Guzmán
- Immunology Laboratory, Institute of Experimental Medicine, National Academy of Medicine/CONICET, Buenos Aires, Argentina
| | - Mirta N Giordano
- Immunology Laboratory, Institute of Experimental Medicine, National Academy of Medicine/CONICET, Buenos Aires, Argentina
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de Andrade FA, Fiorot SHS, Benchimol EI, Provenzano J, Martins VJ, Levy RA. The autoimmune diseases of the eyes. Autoimmun Rev 2016; 15:258-71. [DOI: 10.1016/j.autrev.2015.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 11/27/2015] [Indexed: 02/06/2023]
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16
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Lacritin Salvages Human Corneal Epithelial Cells from Lipopolysaccharide Induced Cell Death. Sci Rep 2015; 5:18362. [PMID: 26670139 PMCID: PMC4680935 DOI: 10.1038/srep18362] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/12/2015] [Indexed: 02/07/2023] Open
Abstract
Innate immunity of the corneal epithelium is conferred by proteinaceous secretions from the epithelium and associated lacrimal and meibomian glands. Lacritin, an eye-specific protein with anti-microbial, cytoprotective and wound-healing properties, predominantly secreted by lacrimal glands, is absent in conditions such as Dry eye and Keratitis. In view of the biological significance of lacritin in human eye, we investigated its role in human corneal epithelial (HCE) cells during lipopolysaccharide (LPS)-induced infection. LPS-challenged HCE cells demonstrated apoptosis-mediated cell death and elevated lacritin levels. The LPS-induced cell death is alleviated with exogenous supplementation of recombinant lacritin. This cytoprotective effect of lacritin is mediated through Cyclooxygenase-2 (COX-2). This study is the first to highlight the protective role of lacritin and mechanism of its action during bacterial infection of cornea in vitro.
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Pseudomonas aeruginosa Survival at Posterior Contact Lens Surfaces after Daily Wear. Optom Vis Sci 2015; 92:659-64. [PMID: 25955639 DOI: 10.1097/opx.0000000000000597] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Pseudomonas aeruginosa keratitis is a sight-threatening complication of contact lens wear, yet mechanisms by which lenses predispose to infection remain unclear. Here, we tested the hypothesis that tear fluid at the posterior contact lens surface can lose antimicrobial activity over time during lens wear. METHODS Daily disposable lenses were worn for 1, 2, 4, 6, or 8 hours immediately after removal from their packaging or after presoaking in sterile saline for 2 days to remove packaging solution. Unworn lenses were also tested, some coated in tears "aged" in vitro for 1 or 8 hours. Lenses were placed anterior surface down into tryptic soy agar cradles containing gentamicin (100 μg/mL) to kill bacteria already on the lens and posterior surfaces inoculated with gentamicin-resistant P. aeruginosa for 3 hours. Surviving bacteria were enumerated by viable counts of lens homogenates. RESULTS Posterior surfaces of lenses worn by patients for 8 hours supported more P. aeruginosa growth than lenses worn for only 1 hour, if lenses were presoaked before wear (∼ 2.4-fold, p = 0.01). This increase was offset if lenses were not presoaked to remove packaging solution (p = 0.04 at 2 and 4 hours). Irrespective of presoaking, lenses worn for 8 hours showed more growth on their posterior surface than unworn lenses coated with tear fluid that was aged for 8 hours in vitro (∼ 8.6-fold, presoaked, p = 0.003; ∼ 5.4-fold from packaging solution, p = 0.004). Indeed, in vitro incubation did not impact tear antimicrobial activity. CONCLUSIONS This study shows that postlens tear fluid can lose antimicrobial activity over time during contact lens wear, supporting the idea that efficient tear exchange under a lens is critical for homeostasis. Additional studies are needed to determine applicability to other lens types, wearing modalities, and relevance to contact lens-related infections.
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Bolaños-Jiménez R, Navas A, López-Lizárraga EP, de Ribot FM, Peña A, Graue-Hernández EO, Garfias Y. Ocular Surface as Barrier of Innate Immunity. Open Ophthalmol J 2015; 9:49-55. [PMID: 26161163 PMCID: PMC4484240 DOI: 10.2174/1874364101509010049] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 04/06/2015] [Accepted: 04/13/2015] [Indexed: 01/08/2023] Open
Abstract
Sight is one of the most important senses that human beings possess. The ocular system is a complex structure equipped with mechanisms that prevent or limit damage caused by physical, chemical, infectious and environmental factors. These mechanisms include a series of anatomical, cellular and humoral factors that have been a matter of study. The cornea is not only the most powerful and important lens of the optical system, but also, it has been involved in many other physiological and pathological processes apart from its refractive nature; the morphological and histological properties of the cornea have been thoroughly studied for the last fifty years; drawing attention in its molecular characteristics of immune response. This paper will review the anatomical and physiological aspects of the cornea, conjunctiva and lacrimal apparatus, as well as the innate immunity at the ocular surface.
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Affiliation(s)
- Rodrigo Bolaños-Jiménez
- Research Unit, Institute of Ophthalmology, Conde de Valenciana Foundation, Chimalpopoca 14, Obrera, CP 06800, Mexico City, México ; Ophthalmology Department, Regional Hospital, Adolfo López Mateos, ISSSTE, México City, México
| | - Alejandro Navas
- Research Unit, Institute of Ophthalmology, Conde de Valenciana Foundation, Chimalpopoca 14, Obrera, CP 06800, Mexico City, México ; Department of Cataract and refractive surgery, Institute of Ophthalmology, Conde de Valenciana Foundation, Mexico City, México
| | - Erika Paulina López-Lizárraga
- Department of Cataract and refractive surgery, Institute of Ophthalmology, Conde de Valenciana Foundation, Mexico City, México
| | - Francesc March de Ribot
- Department of Retina, Institute of Ophthalmology, Conde de Valenciana Foundation, Mexico City, México
| | - Alexandra Peña
- Ophthalmology Department, Regional Hospital, Adolfo López Mateos, ISSSTE, México City, México
| | - Enrique O Graue-Hernández
- Research Unit, Institute of Ophthalmology, Conde de Valenciana Foundation, Chimalpopoca 14, Obrera, CP 06800, Mexico City, México ; Department of Cataract and refractive surgery, Institute of Ophthalmology, Conde de Valenciana Foundation, Mexico City, México
| | - Yonathan Garfias
- Research Unit, Institute of Ophthalmology, Conde de Valenciana Foundation, Chimalpopoca 14, Obrera, CP 06800, Mexico City, México ; Department of Biochemistry, Faculty of Medicine, Universidad Nacional Autónoma de México, 04510. Mexico City, Mexico
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The importance of the Pseudomonas aeruginosa type III secretion system in epithelium traversal depends upon conditions of host susceptibility. Infect Immun 2015; 83:1629-40. [PMID: 25667266 DOI: 10.1128/iai.02329-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pseudomonas aeruginosa is invasive or cytotoxic to host cells, depending on the type III secretion system (T3SS) effectors encoded. While the T3SS is known to be involved in disease in vivo, how it participates remains to be clarified. Here, mouse models of superficial epithelial injury (tissue paper blotting with EGTA treatment) and immunocompromise (MyD88 deficiency) were used to study the contribution of the T3SS transcriptional activator ExsA to epithelial traversal. Corneas of excised eyeballs were inoculated with green fluorescent protein (GFP)-expressing PAO1 or isogenic exsA mutants for 6 h ex vivo before bacterial traversal and epithelial thickness were quantified by using imaging. In the blotting-EGTA model, exsA mutants were defective in capacity for traversal. Accordingly, an ∼16-fold variability in exsA expression among PAO1 isolates from three sources correlated with epithelial loss. In contrast, MyD88-/- epithelia remained susceptible to P. aeruginosa traversal despite exsA mutation. Epithelial lysates from MyD88-/- mice had reduced antimicrobial activity compared to those from wild-type mice with and without prior antigen challenge, particularly 30- to 100-kDa fractions, for which mass spectrometry revealed multiple differences, including (i) lower baseline levels of histones, tubulin, and lumican and (ii) reduced glutathione S-transferase, annexin, and dermatopontin, after antigen challenge. Thus, the importance of ExsA in epithelial traversal by invasive P. aeruginosa depends on the compromise enabling susceptibility, suggesting that strategies for preventing infection will need to extend beyond targeting the T3SS. The data also highlight the importance of mimicking conditions allowing susceptibility in animal models and the need to monitor variability among bacterial isolates from different sources, even for the same strain.
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Abstract
: Clinician-scientists bridge the gap between basic research and patient care. At the 2012 Annual Meeting, a symposium highlighting the application of cutting-edge optometric research within the anterior segment was held to present and discuss some of the recent basic scientific advances that will both shape and guide the development of future clinical care practices. This article summarizes this work, bringing together four experts, all clinician-scientists in the field of cornea and ocular surface. Collectively, this work provides new insights to clinicians and researchers alike, as well as brings forth a greater appreciation of the impact of ongoing optometric bench research in advancing clinical care.
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McDermott AM. Antimicrobial compounds in tears. Exp Eye Res 2013; 117:53-61. [PMID: 23880529 PMCID: PMC3844110 DOI: 10.1016/j.exer.2013.07.014] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 07/11/2013] [Accepted: 07/13/2013] [Indexed: 01/30/2023]
Abstract
The tear film coats the cornea and conjunctiva and serves several important functions. It provides lubrication, prevents drying of the ocular surface epithelia, helps provide a smooth surface for refracting light, supplies oxygen and is an important component of the innate defense system of the eye providing protection against a range of potential pathogens. This review describes both classic antimicrobial compounds found in tears such as lysozyme and some more recently identified such as members of the cationic antimicrobial peptide family and surfactant protein-D as well as potential new candidate molecules that may contribute to antimicrobial protection. As is readily evident from the literature review herein, tears, like all mucosal fluids, contain a plethora of molecules with known antimicrobial effects. That all of these are active in vivo is debatable as many are present in low concentrations, may be influenced by other tear components such as the ionic environment, and antimicrobial action may be only one of several activities ascribed to the molecule. However, there are many studies showing synergistic/additive interactions between several of the tear antimicrobials and it is highly likely that cooperativity between molecules is the primary way tears are able to afford significant antimicrobial protection to the ocular surface in vivo. In addition to effects on pathogen growth and survival some tear components prevent epithelial cell invasion and promote the epithelial expression of innate defense molecules. Given the protective role of tears a number of scenarios can be envisaged that may affect the amount and/or activity of tear antimicrobials and hence compromise tear immunity. Two such situations, dry eye disease and contact lens wear, are discussed here.
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Affiliation(s)
- Alison M McDermott
- University of Houston, College of Optometry, 4901 Calhoun Road, 505 J Davis Armistead Bldg, Houston, TX 77204-2020, USA.
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Surfactant protein D contributes to ocular defense against Pseudomonas aeruginosa in a murine model of dry eye disease. PLoS One 2013; 8:e65797. [PMID: 23762428 PMCID: PMC3675081 DOI: 10.1371/journal.pone.0065797] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 05/02/2013] [Indexed: 01/08/2023] Open
Abstract
Dry eye disease can cause ocular surface inflammation that disrupts the corneal epithelial barrier. While dry eye patients are known to have an increased risk of corneal infection, it is not known whether there is a direct causal relationship between these two conditions. Here, we tested the hypothesis that experimentally-induced dry eye (EDE) increases susceptibility to corneal infection using a mouse model. In doing so, we also examined the role of surfactant protein D (SP-D), which we have previously shown is involved in corneal defense against infection. Scopolamine injections and fan-driven air were used to cause EDE in C57BL/6 or Black Swiss mice (wild-type and SP-D gene-knockout). Controls received PBS injections and were housed normally. After 5 or 10 days, otherwise uninjured corneas were inoculated with 10(9) cfu of Pseudomonas aeruginosa strain PAO1. Anesthesia was maintained for 3 h post-inoculation. Viable bacteria were quantified in ocular surface washes and corneal homogenates 6 h post-inoculation. SP-D was measured by Western immunoblot, and corneal pathology assessed from 6 h to 4 days. EDE mice showed reduced tear volumes after 5 and 10 days (each by ∼75%, p<0.001) and showed fluorescein staining (i.e. epithelial disruption). Surprisingly, there was no significant difference in corneal pathology between EDE mice and controls (∼10-14% incidence). Before bacterial inoculation, EDE mice showed elevated SP-D in ocular washes. After inoculation, fewer bacteria were recovered from ocular washes of EDE mice (<2% of controls, p = 0.0004). Furthermore, SP-D knockout mice showed a significant increase in P. aeruginosa corneal colonization under EDE conditions. Taken together, these data suggest that SP-D contributes to corneal defense against P. aeruginosa colonization and infection in EDE despite the loss of barrier function to fluorescein.
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Evans DJ, Fleiszig SM. Why does the healthy cornea resist Pseudomonas aeruginosa infection? Am J Ophthalmol 2013; 155:961-970.e2. [PMID: 23601656 DOI: 10.1016/j.ajo.2013.03.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 03/01/2013] [Accepted: 03/04/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE To provide our perspective on why the cornea is resistant to infection based on our research results with Pseudomonas (P) aeruginosa. We focus on our current understanding of the interplay between bacteria, tear fluid, and the corneal epithelium that determines health as the usual outcome, and propose a theoretical model for how contact lens wear might change those interactions to enable susceptibility to P aeruginosa infection. METHODS Use of "null-infection" in vivo models, cultured human corneal epithelial cells, contact lens-wearing animal models, and bacterial genetics help to elucidate mechanisms by which P aeruginosa survives at the ocular surface, adheres, and traverses multilayered corneal epithelia. These models also help elucidate the molecular mechanisms of corneal epithelial innate defense. RESULTS Tear fluid and the corneal epithelium combine to make a formidable defense against P aeruginosa infection of the cornea. Part of that defense involves the expression of antimicrobials such as β-defensins, the cathelicidin LL-37, cytokeratin-derived antimicrobial peptides, and RNase7. Immunomodulators such as SP-D and ST2 also contribute. Innate defenses of the cornea depend in part on MyD88, a key adaptor protein of TLR and IL-1R signaling, but the basal lamina represents the final barrier to bacterial penetration. Overcoming these defenses involves P aeruginosa adaptation, expression of the type III secretion system, proteases, and P aeruginosa biofilm formation on contact lenses. CONCLUSION After more than 2 decades of research focused on understanding how contact lens wear predisposes to P aeruginosa infection, our working hypothesis places blame for microbial keratitis on bacterial adaptation to ocular surface defenses, combined with changes to the biochemistry of the corneal surface caused by trapping bacteria and tear fluid against the cornea under the lens.
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Abstract
Microbial keratitis is a sight-threatening complication associated with contact lenses. The introduction of silicone hydrogel lens materials with increased oxygen transmission to the ocular surface has not significantly altered the incidence of microbial keratitis. These data suggest that alternate, or additional, predisposing factors involving lens wear must be addressed to reduce or eliminate these infections. The contact lens can provide a surface for microbial growth in situ and can also influence ocular surface homeostasis through effects on the tear fluid and corneal epithelium. Thus, it is intuitive that future contact lens materials could make a significant contribution to preventing microbial keratitis. Design of the "right" material to prevent microbial keratitis requires understanding the effects of current materials on bacterial virulence in the cornea and on ocular surface innate defenses. Current knowledge in each of these areas will be presented with a discussion of future directions needed to understand the influence of lens material on the pathogenesis of microbial keratitis.
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Mun J, Tam C, Chan G, Kim JH, Evans D, Fleiszig S. MicroRNA-762 is upregulated in human corneal epithelial cells in response to tear fluid and Pseudomonas aeruginosa antigens and negatively regulates the expression of host defense genes encoding RNase7 and ST2. PLoS One 2013; 8:e57850. [PMID: 23469087 PMCID: PMC3585208 DOI: 10.1371/journal.pone.0057850] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 01/27/2013] [Indexed: 12/21/2022] Open
Abstract
Mucosal surfaces regulate defenses against infection and excessive inflammation. We previously showed that human tears upregulated epithelial expression of genes encoding RNase7 and ST2, which inhibited Pseudomonas aeruginosa invasion of human corneal epithelial cells. Here, microRNA microarrays were used to show that a combination of tear fluid exposure (16 h) then P. aeruginosa antigens (3 h) upregulated miR-762 and miR-1207, and down-regulated miR-92 and let-7b (all > 2-fold) in human corneal epithelial cells compared to P. aeruginosa antigens alone. RT-PCR confirmed miR-762 upregulation ∼ 3-fold in tear-antigen exposed cells. Without tears or antigens, an antagomir reduced miR-762 expression relative to scrambled controls by ∼50%, increased expression of genes encoding RNase7 (∼80 %), ST2 (∼58%) and Rab5a (∼75%), without affecting P. aeruginosa internalization. However, P. aeruginosa invasion was increased > 3-fold by a miR-762 mimic which reduced RNase7 and ST2 gene expression. Tear fluid alone also induced miR-762 expression ∼ 4-fold, which was reduced by the miR-762 antagomir. Combination of tear fluid and miR-762 antagomir increased RNase7 and ST2 gene expression. These data show that mucosal fluids, such as tears, can modulate epithelial microRNA expression to regulate innate defense genes, and that miR-762 negatively regulates RNase7, ST2 and Rab5a genes. Since RNase7 and ST2 inhibit P. aeruginosa internalization, and are upregulated by tear fluid, other tear-induced mechanisms must counteract inhibitory effects of miR-762 to regulate resistance to bacteria. These data also suggest a complex relationship between tear induction of miR-762, its modulation of innate defense genes, and P. aeruginosa internalization.
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Affiliation(s)
- James Mun
- School of Optometry, University of California, Berkeley, California, United States of America
- Vision Science Program, University of California, Berkeley, California, United States of America
| | - Connie Tam
- School of Optometry, University of California, Berkeley, California, United States of America
| | - Gary Chan
- Program in Bioengineering, University of California, Berkeley, California, United States of America
| | - Jong Hun Kim
- Program in Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - David Evans
- School of Optometry, University of California, Berkeley, California, United States of America
- College of Pharmacy, Touro University California, Vallejo, California, United States of America
| | - Suzanne Fleiszig
- School of Optometry, University of California, Berkeley, California, United States of America
- Vision Science Program, University of California, Berkeley, California, United States of America
- Graduate Groups in Microbiology and Infectious Disease, University of California, Berkeley, California, United States of America
- * E-mail:
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27
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Morgan PB, Bright FV, Burke SE, Chalmers RL, Dobson C, Fleiszig SM, Hutter JC, Papas E, Peterson RC, Stapleton F. 4. Contemporary research in contact lens care. Cont Lens Anterior Eye 2013; 36 Suppl 1:S22-7. [PMID: 23347572 DOI: 10.1016/s1367-0484(13)60006-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Tam C, LeDue J, Mun JJ, Herzmark P, Robey EA, Evans DJ, Fleiszig SMJ. 3D quantitative imaging of unprocessed live tissue reveals epithelial defense against bacterial adhesion and subsequent traversal requires MyD88. PLoS One 2011; 6:e24008. [PMID: 21901151 PMCID: PMC3162028 DOI: 10.1371/journal.pone.0024008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 08/03/2011] [Indexed: 12/15/2022] Open
Abstract
While a plethora of in vivo models exist for studying infectious disease and its resolution, few enable factors involved in the maintenance of health to be studied in situ. This is due in part to a paucity of tools for studying subtleties of bacterial-host interactions at a cellular level within live organs or tissues, requiring investigators to rely on overt outcomes (e.g. pathology) in their research. Here, a suite of imaging technologies were combined to enable 3D and temporal subcellular localization and quantification of bacterial distribution within the murine cornea without the need for tissue processing or dissection. These methods were then used to demonstrate the importance of MyD88, a central adaptor protein for Toll-Like Receptor (TLR) mediated signaling, in protecting a multilayered epithelium against both adhesion and traversal by the opportunistic bacterial pathogen Pseudomonas aeruginosa ex vivo and in vivo.
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Affiliation(s)
- Connie Tam
- School of Optometry, University of California, Berkeley, California, United States of America
| | - Jeffrey LeDue
- School of Optometry, University of California, Berkeley, California, United States of America
| | - James J. Mun
- Program in Vision Science, University of California, Berkeley, California, United States of America
| | - Paul Herzmark
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Ellen A. Robey
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - David J. Evans
- School of Optometry, University of California, Berkeley, California, United States of America
- College of Pharmacy, Touro University California, Vallejo, California, United States of America
| | - Suzanne M. J. Fleiszig
- School of Optometry, University of California, Berkeley, California, United States of America
- Program in Vision Science, University of California, Berkeley, California, United States of America
- Programs in Infectious Diseases and Immunity and Microbiology, University of California, Berkeley, California, United States of America
- * E-mail:
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