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Glasgow BJ. Tear Lipocalin and Lipocalin-Interacting Membrane Receptor. Front Physiol 2021; 12:684211. [PMID: 34489718 PMCID: PMC8417070 DOI: 10.3389/fphys.2021.684211] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/13/2021] [Indexed: 11/24/2022] Open
Abstract
Tear lipocalin is a primate protein that was recognized as a lipocalin from the homology of the primary sequence. The protein is most concentrated in tears and produced by lacrimal glands. Tear lipocalin is also produced in the tongue, pituitary, prostate, and the tracheobronchial tree. Tear lipocalin has been assigned a multitude of functions. The functions of tear lipocalin are inexorably linked to structural characteristics that are often shared by the lipocalin family. These characteristics result in the binding and or transport of a wide range of small hydrophobic molecules. The cavity of tear lipocalin is formed by eight strands (A-H) that are arranged in a β-barrel and are joined by loops between the β-strands. Recently, studies of the solution structure of tear lipocalin have unveiled new structural features such as cation-π interactions, which are extant throughout the lipocalin family. Lipocalin has many unique features that affect ligand specificity. These include a capacious and a flexible cavity with mobile and short overhanging loops. Specific features that confer promiscuity for ligand binding in tear lipocalin will be analyzed. The functions of tear lipocalin include the following: antimicrobial activities, scavenger of toxic and tear disruptive compounds, endonuclease activity, and inhibition of cysteine proteases. In addition, tear lipocalin binds and may modulate lipids in the tears. Such actions support roles as an acceptor for phospholipid transfer protein, heteropolymer formation to alter viscosity, and tear surface interactions. The promiscuous lipid-binding properties of tear lipocalin have created opportunities for its use as a drug carrier. Mutant analogs have been created to bind other molecules such as vascular endothelial growth factor for medicinal use. Tear lipocalin has been touted as a useful biomarker for several diseases including breast cancer, chronic obstructive pulmonary disease, diabetic retinopathy, and keratoconus. The functional possibilities of tear lipocalin dramatically expanded when a putative receptor, lipocalin-interacting membrane receptor was identified. However, opposing studies claim that lipocalin-interacting membrane receptor is not specific for lipocalin. A recent study even suggests a different function for the membrane protein. This controversy will be reviewed in light of gene expression data, which suggest that tear lipocalin has a different tissue distribution than the putative receptor. But the data show lipocalin-interacting membrane receptor is expressed on ocular surface epithelium and that a receptor function here would be rational.
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Affiliation(s)
- Ben J. Glasgow
- Departments of Ophthalmology, Pathology and Laboratory Medicine, Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
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Wang JY, Kwon JS, Hsu SM, Chuang HS. Sensitive tear screening of diabetic retinopathy with dual biomarkers enabled using a rapid electrokinetic patterning platform. LAB ON A CHIP 2020; 20:356-362. [PMID: 31848562 DOI: 10.1039/c9lc00975b] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bead-based immunosensors have intrigued the scientific community over the past decades due to their rapid and multiplexed capabilities in the detection of various biological targets. Nevertheless, their use in the detection of low-abundance analytes remains a continuing challenge because of their limited number of active enrichment approaches. To this end, our research presents a delicate microbead enrichment technique using an optoelectrokinetic platform, followed by the detection of dual biomarkers for the sensitive screening of an eye disease termed diabetic retinopathy (DR). In this study, microbeads turned fluorescent as their surfaces formed sandwiched immunocomplexes in the presence of target antigens. The tiny fluorescent dots were then concentrated using the optoelectrokinetic platform for the enhancement of their signals. The signal rapidly escalated in 10 s, and the optimal limit of detection was nearly 100 pg mL-1. For practical DR screening, two biomarkers, lipocalin 1 (LCN1) and vascular endothelial growth factor (VEGF), were used. Approximately 20 μL of analytes were collected from the tear samples of the tested patients. The concentrations of both biomarkers showed escalating trends with the severity of DR. Two concentration thresholds of LCN1 and VEGF that indicate proliferative DR were determined out of 24 clinical samples based on the receiver operating characteristic curves. For verification, a single-blind test was conducted with additional clinical tear samples from five random subjects. The final outcome of this evaluation showed an accuracy of >80%. This non-invasive screening provides a potential means for the early diagnosis of DR and may increase the screening rate among the high-risk diabetic population in the future.
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Affiliation(s)
- Jen-Yi Wang
- Department of Biomedical Engineering, National Cheng Kung University, Taiwan
| | - Jae-Sung Kwon
- Division of Thermal and Fluids Science, Institute for Computational Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam. and Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam and Department of Mechanical Engineering, Incheon National University, Incheon, Republic of Korea.
| | - Sheng-Min Hsu
- Department of Ophthalmology, National Cheng Kung University Hospital, Taiwan
| | - Han-Sheng Chuang
- Department of Biomedical Engineering, National Cheng Kung University, Taiwan and Center for Micro/Nano Science and Technology, National Cheng Kung University, Taiwan.
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Kim JH, Kang JW, Choi MG, Lee KW, Kim JC. Changes in Total Tear Protein and Lipocalin Concentration According to Frequency of Artificial Tear Usage. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2019. [DOI: 10.3341/jkos.2019.60.5.414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
| | - Jeong Woo Kang
- Department of Ophthalmology, Chung-Ang University College of Medicine, Seoul, Korea
| | - Min Gyu Choi
- Department of Ophthalmology, Chung-Ang University College of Medicine, Seoul, Korea
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Jia W, Lu Z, Yang H, Li H, Xu D. Elimination terminal fixed region screening and high-throughput kinetic determination of aptamer for lipocalin-1 by surface plasmon resonance imaging. Anal Chim Acta 2018; 1043:158-166. [PMID: 30392664 DOI: 10.1016/j.aca.2018.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/31/2018] [Accepted: 09/10/2018] [Indexed: 12/31/2022]
Abstract
A highly efficient method for eliminating terminal fixed region interference of aptamer with real-time monitoring of the SELEX process was described by silver decahedra nanoparticles probe (Ag10-A10-RP(15)) capture and block the terminal fixed region candidates. A microarray chip was developed by immobilization of target protein (lipocalin-1 (LCN-1)) and control proteins (Human serum albumin (HSA), Bovine serum albumin (BSA) and Holo-transferrin) on the biochip surface. The nucleic acid pool was first incubated with target and then captured by hybridization with Ag10-A10-RP(15). The work allows rapid screening of aptamer elimination fixed-region interference, and the kinetic constants of candidate sequences can be quickly determined using SPRi technology. Eventually, ten aptamers with high affinity and specific for LCN-1 after only fifth-round of selection was acquired.
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Affiliation(s)
- Wenchao Jia
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Zhongyi Lu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Hao Yang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Hui Li
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China
| | - Danke Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China.
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Detection of low-abundance biomarker lipocalin 1 for diabetic retinopathy using optoelectrokinetic bead-based immunosensing. Biosens Bioelectron 2017; 89:701-709. [DOI: 10.1016/j.bios.2016.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 10/27/2016] [Accepted: 11/07/2016] [Indexed: 12/26/2022]
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Wang JC, Ku HY, Shieh DB, Chuang HS. A bead-based fluorescence immunosensing technique enabled by the integration of Förster resonance energy transfer and optoelectrokinetic concentration. BIOMICROFLUIDICS 2016; 10:014113. [PMID: 26865906 PMCID: PMC4733077 DOI: 10.1063/1.4940938] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/17/2016] [Indexed: 05/04/2023]
Abstract
Bead-based immunosensing has been growing as a promising technology in the point-of-care diagnostics due to great flexibility. For dilute samples, functionalized particles can be used to collect dispersed analytes and act as carriers for particle manipulation. To realize rapid and visual immunosensing, Förster resonance energy transfer (FRET) was used herein to ensure only the diabetic biomarker, lipocalin 1, to be detected. The measurement was made in an aqueous droplet sandwiched between two parallel plate electrodes. With an electric field and a focused laser beam applying on the microchip simultaneously, the immunocomplexes in the droplet were further concentrated to enhance the FRET fluorescent signal. The optoelectrokinetic technique, termed rapid electrokinetic patterning (REP), has been proven to be excellent in dynamic and programmable particle manipulation. Therefore, the detection can be complete within several tens of seconds. The lower detection limit of the REP-enabled bead-based diagnosis reached nearly 5 nM. The combinative use of FRET and the optoelectrokinetic technique for the bead-based immunosensing enables a rapid measure to diagnose early stage diseases and dilute analytes.
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Affiliation(s)
| | - Hu-Yao Ku
- Department of Biomedical Engineering, National Cheng Kung University , Tainan, Taiwan
| | - Dar-Bin Shieh
- Medical Device Innovation Center, National Cheng Kung University , Tainan, Taiwan
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Tucker RM, Mattes RD, Running CA. Mechanisms and effects of "fat taste" in humans. Biofactors 2014; 40:313-26. [PMID: 24591077 DOI: 10.1002/biof.1162] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 02/18/2014] [Indexed: 12/11/2022]
Abstract
Evidence supporting a "taste" cue from fat in the oral cavity continues to accrue. The proposed stimuli for fat taste, non-esterified fatty acids (NEFA), are released from food through hydrolytic rancidity and lipase activity derived from foods or saliva. NEFA must then be released from the food matrix, negotiate the aqueous environment to reach taste cell surfaces, and interact with receptors such as CD36 and GPR120 or diffuse across cell membranes to initiate a taste signal. Knowledge of these processes in non-gustatory tissues should inform understanding of taste responses to NEFA. Additionally, downstream effects of oral triglyceride exposure have been observed in numerous studies. Data specific to effects of NEFA versus triglyceride are scarce, but modified sham feeding trials with triglyceride document cephalic phase responses including elevations in serum lipids and insulin as well as potential, but debated, effects on gut peptides, appetite, and thermogenesis. In this review, we highlight the mechanisms by which NEFA migrate to and interact with taste cells, and then we examine physiological responses to oral fat exposure.
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Affiliation(s)
- Robin M Tucker
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
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Targeting iron acquisition blocks infection with the fungal pathogens Aspergillus fumigatus and Fusarium oxysporum. PLoS Pathog 2013; 9:e1003436. [PMID: 23853581 PMCID: PMC3708856 DOI: 10.1371/journal.ppat.1003436] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 05/02/2013] [Indexed: 12/21/2022] Open
Abstract
Filamentous fungi are an important cause of pulmonary and systemic morbidity and mortality, and also cause corneal blindness and visual impairment worldwide. Utilizing in vitro neutrophil killing assays and a model of fungal infection of the cornea, we demonstrated that Dectin-1 dependent IL-6 production regulates expression of iron chelators, heme and siderophore binding proteins and hepcidin in infected mice. In addition, we show that human neutrophils synthesize lipocalin-1, which sequesters fungal siderophores, and that topical lipocalin-1 or lactoferrin restricts fungal growth in vivo. Conversely, we show that exogenous iron or the xenosiderophore deferroxamine enhances fungal growth in infected mice. By examining mutant Aspergillus and Fusarium strains, we found that fungal transcriptional responses to low iron levels and extracellular siderophores are essential for fungal growth during infection. Further, we showed that targeting fungal iron acquisition or siderophore biosynthesis by topical application of iron chelators or statins reduces fungal growth in the cornea by 60% and that dual therapy with the iron chelator deferiprone and statins further restricts fungal growth by 75%. Together, these studies identify specific host iron-chelating and fungal iron-acquisition mediators that regulate fungal growth, and demonstrate that therapeutic inhibition of fungal iron acquisition can be utilized to treat topical fungal infections.
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Lacritin and the tear proteome as natural replacement therapy for dry eye. Exp Eye Res 2013; 117:39-52. [PMID: 23769845 DOI: 10.1016/j.exer.2013.05.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/23/2013] [Accepted: 05/31/2013] [Indexed: 12/21/2022]
Abstract
Tear proteins are potential biomarkers, drug targets, and even biotherapeutics. As a biotherapeutic, a recombinant tear protein might physiologically rescue the ocular surface when a deficiency is detected. Such a strategy pays more attention to the natural prosecretory and protective properties of the tear film and seeks to alleviate symptoms by addressing cause, rather than the current palliative, non-specific and temporary approaches. Only a handful of tear proteins appear to be selectively downregulated in dry eye, the most common eye disease. Lacritin and lipocalin-1 are two tear proteins selectively deficient in dry eye. Both proteins influence ocular surface health. Lacritin is a prosecretory mitogen that promotes basal tearing when applied topically. Levels of active monomeric lacritin are negatively regulated by tear tissue transglutaminase, whose expression is elevated in dry eye with ocular surface inflammation. Lipocalin-1 is the master lipid sponge of the ocular surface, without which residual lipids could interfere with epithelial wetting. It also is a carrier for vitamins and steroid hormones, and is a key endonuclease. Accumulation of DNA in tears is thought to be proinflammatory. Functions of these and other tear proteins may be influenced by protein-protein interactions. Here we discuss new advances in lacritin biology and provide an overview on lipocalin-1, and newly identified members of the tear proteome.
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Ubels JL, Gipson IK, Spurr-Michaud SJ, Tisdale AS, Van Dyken RE, Hatton MP. Gene expression in human accessory lacrimal glands of Wolfring. Invest Ophthalmol Vis Sci 2012; 53:6738-47. [PMID: 22956620 DOI: 10.1167/iovs.12-10750] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The accessory lacrimal glands are assumed to contribute to the production of tear fluid, but little is known about their function. The goal of this study was to conduct an analysis of gene expression by glands of Wolfring that would provide a more complete picture of the function of these glands. METHODS Glands of Wolfring were isolated from frozen sections of human eyelids by laser microdissection. RNA was extracted from the cells and hybridized to gene expression arrays. The expression of several of the major genes was confirmed by immunohistochemistry. RESULTS Of the 24 most highly expressed genes, 9 were of direct relevance to lacrimal function. These included lysozyme, lactoferrin, tear lipocalin, and lacritin. The glands of Wolfring are enriched in genes related to protein synthesis, targeting, and secretion, and a large number of genes for proteins with antimicrobial activity were detected. Ion channels and transporters, carbonic anhydrase, and aquaporins were abundantly expressed. Genes for control of lacrimal function, including cholinergic, adrenergic, vasoactive intestinal polypeptide, purinergic, androgen, and prolactin receptors were also expressed in gland of Wolfring. CONCLUSIONS The data suggest that the function of glands of Wolfring is similar to that of main lacrimal glands and are consistent with secretion electrolytes, fluid, and protein under nervous and hormonal control. Since these glands secrete directly onto the ocular surface, their location may allow rapid response to exogenous stimuli and makes them readily accessible to topical drugs.
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Affiliation(s)
- John L Ubels
- Department of Biology, Calvin College, Grand Rapids, Michigan 49546, USA.
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Kim HJ, Kim PK, Yoo HS, Kim CW. Comparison of tear proteins between healthy and early diabetic retinopathy patients. Clin Biochem 2011; 45:60-7. [PMID: 22040812 DOI: 10.1016/j.clinbiochem.2011.10.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/11/2011] [Accepted: 10/14/2011] [Indexed: 10/16/2022]
Abstract
OBJECTIVES To identify potential prognostic or diagnostic marker tear proteins for early diabetic retinopathy (DR) and to investigate the pathogenesis of this disease using proteomics techniques. DESIGN AND METHODS The tear proteins expressed in patients suffering from diabetes mellitus without the retinopathy symptoms, nonproliferative diabetic retinopathy and healthy volunteers were analyzed by 2-DE. The differentially expressed proteins in patients were identified by ESI-Q-TOF and confirmed by Western blotting. RESULTS Proteins which were differentially expressed with statistical significance (P<0.05) in two diabetic groups as compared to those in healthy group were selected and identified by ESI-Q-TOF MS/MS. Among these proteins, three proteins (LCN-1, HSP27 and B2M) were found to exhibit a progressive reduction in two disease groups. The expression levels of which might be useful as diagnostic biomarkers of DR were verified by Western blotting CONCLUSIONS Proteomic analysis using tear is a novel approach that can provide insight into possible biomarker and the pathogenesis of early DR.
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Affiliation(s)
- Hyun-Jung Kim
- School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
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Srinivasan S, Joyce E, Boone A, Simpson T, Jones L, Senchyna M. Tear lipocalin and lysozyme concentrations in postmenopausal women. Ophthalmic Physiol Opt 2010; 30:257-66. [DOI: 10.1111/j.1475-1313.2010.00714.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Zhao Z, Liu J, Wasinger VC, Malouf T, Nguyen-Khuong T, Walsh B, Willcox MD. Tear lipocalin is the predominant phosphoprotein in human tear fluid. Exp Eye Res 2010; 90:344-9. [DOI: 10.1016/j.exer.2009.11.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 11/19/2009] [Accepted: 11/23/2009] [Indexed: 10/20/2022]
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Glasier MA, Subbaraman LN, Senchyna M, Jones L. A Solid-Phase Assay for the Quantitation of Total Protein Eluted from Balafilcon, Lotrafilcon, and Etafilcon Contact Lenses. Curr Eye Res 2009; 33:631-40. [DOI: 10.1080/02713680802291537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Mary-Ann Glasier
- Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
| | - Lakshman N. Subbaraman
- Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Lyndon Jones
- Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada
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Glasier MA, Keech A, Sheardown H, Subbaraman LN, Jones L. Conformational and Quantitative Characterization of Lysozyme Extracted from Galyfilcon and Senofilcon Silicone Hydrogel Contact Lenses. Curr Eye Res 2009; 33:1-11. [DOI: 10.1080/02713680701830278] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Millar TJ, Mudgil P, Butovich IA, Palaniappan CK. Adsorption of human tear lipocalin to human meibomian lipid films. Invest Ophthalmol Vis Sci 2008; 50:140-51. [PMID: 18757516 DOI: 10.1167/iovs.08-2097] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Tear lipocalin (Tlc) is a major lipid binding protein in tears and is thought to have an important role in stabilizing the Meibomian lipid layer by transferring lipids to it from the aqueous layer or ocular surface, or by adsorbing to it directly. These possible roles have been investigated in vitro using human Tlc. METHODS Tlc was purified from human tears by size exclusion chromatography followed by ion exchange chromatography. Three additional samples of the Tlc were prepared by lipidation, delipidation, and relipidation. The lipids extracted from the purified Tlc were analyzed by HPLC-MS followed by fragmentation. Adsorption of these different forms of Tlc to a human Meibomian lipid film spread on the surface of an artificial tear buffer in a Langmuir trough were observed by recording changes in the pressure with time (Pi-T profile) and monitoring the appearance of the film microscopically. These results were compared with similar experiments using a bovine Meibomian lipid film. RESULTS The results indicated that Tlc binds slowly to a human Meibomian lipid film compared with lysozyme or lactoferrin, even at 37 degrees C. The adsorption of Tlc to a human Meibomian lipid film was very different from its adsorption to a bovine Meibomian lipid film, indicating the nature of the lipids in the film is critical to the adsorption process. Similarly, the different forms of Tlc had quite distinct adsorption patterns, as indicated both by changes in Pi-T profiles and the microscopic appearance of the films. CONCLUSIONS It was concluded that human Tlc was capable of adsorbing to and penetrating into a Meibomian lipid layer, but this process is very complex and depends on both the types of lipids bound to Tlc and the lipid complement comprising the Meibomian lipid film.
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Affiliation(s)
- Thomas J Millar
- School of Natural Sciences, Parramatta Campus, University of Western Sydney, Sydney, New South Wales, Australia.
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Caffery B, Joyce E, Boone A, Slomovic A, Simpson T, Jones L, Senchyna M. Tear Lipocalin and Lysozyme in Sjögren and Non-Sjogren Dry Eye. Optom Vis Sci 2008; 85:661-7. [DOI: 10.1097/opx.0b013e318181ae4f] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Yamada M, Mochizuki H, Kawashima M, Hata S. Phospholipids and Their Degrading Enzyme in the Tears of Soft Contact Lens Wearers. Cornea 2006; 25:S68-72. [PMID: 17001197 DOI: 10.1097/01.ico.0000247217.16510.f2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Low tear phospholipids levels are associated with tear film instability in soft contact lens wearers. We assayed levels of phospholipids and their degrading enzyme secretory phospholipase A2 (sPLA2) both in tears and deposited on contact lenses composed of 2 hydrophilic materials after 1 day of routine use. METHODS Polymacon (Medalist; FDA group 1, low water/nonionic) and Etafilcon A (One Day Acuvue; group 4, high water/ionic) contact lenses were worn for 12 hours by 16 experienced contact lens wearers. Phospholipids in tear fluids and deposited on contact lenses were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Double-antibody sandwich ELISA was used to determine group IIa sPLA2 concentrations, and sPLA2 activity was assayed using 1,2-diheptanoyl thio-phosphatidylcholine as substrate. RESULTS Phospholipids concentrations in tears with Polymacon and Etafilcon A were 186 +/- 39 and 162 +/- 33 microg/mL, respectively. The latter concentration was significantly lower than that observed in the same subjects when not wearing contact lenses (P = 0.0023). In tears, both group IIa sPLA2 concentrations and enzymatic activity remained unchanged, regardless of lens wearing. However, Etafilcon A (0.57 +/- 0.09 microg/lens) showed more group IIa sPLA2 deposition than Polymacon (0.01 +/- 0.01 microg/lens; P < 0.001). Furthermore, group IIa sPLA2 deposited on Etafilcon A but not on Polymacon lenses retained its enzymatic activity. CONCLUSION Significant differences of group IIa sPLA2 deposition were found in the 2 lenses tested. Such deposition might induce phospholipid hydrolysis in tears and thereby promote tear film instability in hydrophilic contact lens wearers.
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Affiliation(s)
- Masakazu Yamada
- Division for Vision Research, National Institute of Sensory Organs, National Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo 152-8902, Japan.
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Gouveia SM, Tiffany JM. Human tear viscosity: An interactive role for proteins and lipids. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1753:155-63. [PMID: 16236563 DOI: 10.1016/j.bbapap.2005.08.023] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2003] [Revised: 08/26/2005] [Accepted: 08/30/2005] [Indexed: 11/20/2022]
Abstract
Human tear viscosity is poorly understood. Tears need to remain on the ocular surface for lubrication without causing damage to the surface epithelia due to drag when blinking. Whole tears are shear-thinning (non-Newtonian), which cannot be explained by the amount of mucin present, nor by individual proteins. Whole tears minus lipids become Newtonian. Though no free lipids had previously been found in collected tears, tear lipocalin (TL), a major tear protein, is known to bind lipids. In this study, we aimed to confirm whether there are any free lipids in collected tears, and to clarify the combined contribution of tear proteins to viscosity, including experiments on recombinant TL, both without (apo-TL) and with (holo-TL) bound lipid. We also investigated possible oligomer formation by holo- and apo-TL as a mechanism for viscosity using SDS-PAGE and analytical ultracentrifugation (AU). For comparison, we have included results for beta-lactoglobulin, a well-characterised lipocalin protein. No free lipids were detected in whole tears. Rheology showed that any protein combination that included lysozyme or lactoferrin was shear-thinning, as was apo-TL, though holo-TL was Newtonian (linear). Results from SDS-PAGE and AU showed apo-TL to be entirely monomeric, but holo-TL showed some dimerization. Both apo- and holo-beta-lactoglobulin exhibited a monomer-dimer equilibrium. We conclude that hetero-protein interactions, possibly electrostatic, involving lipid-binding-induced structural changes to TL, significantly contribute to the viscosity of human tears.
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Affiliation(s)
- Scott M Gouveia
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX2 6AW, UK
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Gasymov OK, Abduragimov AR, Prasher P, Yusifov TN, Glasgow BJ. Tear lipocalin: evidence for a scavenging function to remove lipids from the human corneal surface. Invest Ophthalmol Vis Sci 2005; 46:3589-96. [PMID: 16186338 PMCID: PMC1618769 DOI: 10.1167/iovs.05-0569] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Lipid contamination of the cornea may create an unwettable surface and result in desiccation of the corneal epithelium. Tear lipocalin (TL), also known as lipocalin-1, is the principal lipid-binding protein in tears. TL has been shown to scavenge lipids from hydrophobic surfaces. The hypothesis that TL can remove contaminating fatty acids and phospholipids from the human corneal surface was tested. METHODS TL was purified from pooled human tear samples by size exclusion and ion exchange chromatographies. Tears depleted of TL were reconstituted from fractions eluted by size exclusion chromatography that did not contain TL. Fresh and formalin-fixed human corneas were obtained from exenteration specimens. Fluorescent analogs of either palmitic acid or phosphatidylcholine were applied to the corneal epithelial surface. Tears, TL, or tears depleted of TL were applied over the corneas, and spectrofluorometry and fluorescent stereomicroscopy were used to monitor the removal of fluorescent lipids. Tears used in the experiments were then fractionated by size exclusion chromatography to determine the component of tears associated with fluorescent lipids. RESULTS Significant enhancement of fluorescence for 16AP and NBD C(6)-HPC was evident in solutions incubated with whole tears and purified TL but not with tears depleted of TL for fixed and unfixed corneas. After the experiment, size exclusion fractions of tears showed that the fluorescence component coeluted with TL. CONCLUSIONS TL scavenges lipids from the human corneal surface and delivers them into the aqueous phase of tears. TL may have an important role in removing lipids from the corneal surface to maintain the wettability and integrity of the ocular surface.
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Affiliation(s)
| | | | | | | | - Ben J. Glasgow
- Corresponding author: Ben J. Glasgow, 100 Stein Plaza, Room B-279, Los Angeles, CA 90095;
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Yamada M, Mochizuki H, Kawai M, Tsubota K, Bryce TJ. Decreased tear lipocalin concentration in patients with meibomian gland dysfunction. Br J Ophthalmol 2005; 89:803-5. [PMID: 15965153 PMCID: PMC1772731 DOI: 10.1136/bjo.2004.055822] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND/AIM Recent studies have demonstrated that tear lipocalin (TL) and phospholipids have a crucial role in maintaining tear film stability. The level of TL in patients with meibomian gland dysfunction (MGD) was examined and these data were correlated with the severity of their clinical disorder. METHODS 12 patients with obstructive MGD, 12 patients with seborrhoeic MGD, and 12 age matched normal control subjects participated in this study. 3 mul of unstimulated tears were collected with a micropipette from the inferior tear meniscus in the right eye of all subjects. Tear samples were fractionated by high performance liquid chromatography, and TL concentrations were assayed with a bicinchoninic acid technique. RESULTS The mean concentration of TL in patients with obstructive and seborrhoeic MGD was significantly lower than in normal controls. TL concentration correlated positively with tear film break up time and negatively with fluorescein staining scores. CONCLUSION These results suggest that TL deficiency may be a predisposing factor for the manifestation of symptoms in MGD.
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Affiliation(s)
- M Yamada
- Department of Ophthalmology, Keigo University School of Medicine, Tokyo, Japan.
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Fluckinger M, Haas H, Merschak P, Glasgow BJ, Redl B. Human tear lipocalin exhibits antimicrobial activity by scavenging microbial siderophores. Antimicrob Agents Chemother 2004; 48:3367-72. [PMID: 15328098 PMCID: PMC514737 DOI: 10.1128/aac.48.9.3367-3372.2004] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human tear lipocalin (TL; also known as Lcn1) is a secretory protein present in large amounts in fluids that cover epithelial surfaces such as tears and respiratory secretions. It is supposed to act as a physiological scavenger of hydrophobic, potentially harmful molecules, but there is evidence that it also inhibits bacterial growth. In the present study, we reconsidered the possibility that TL might interfere with microbial growth by scavenging of siderophores, as described for human neutrophil gelatinase-associated lipocalin (NGAL). Indeed, our experiments revealed that TL binds to microbial siderophores with high affinities. In contrast to NGAL, which was shown to have some specificity for bacterial catecholate-type siderophores, TL binds to a broad array of siderophores, including bacterial catecholate-type enterobactin and hydroxamate-type desferrioxamine B, and all major classes of fungal siderophores. By adding exogenous TL, bacterial and fungal growth could be inhibited under iron-limiting conditions. Thus, TL might be a novel member of the innate immune system especially involved in mucosal defense against fungal infections.
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Affiliation(s)
- Maria Fluckinger
- Department of Molecular Biology, Innsbruck Medical University, Peter-Mayr Strasse 4b, A-6020 Innsbruck, Austria
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Glasgow BJ, Abduragimov AR, Gasymov OK, Yusifov TN. Tear lipocalin: structure, function and molecular mechanisms of action. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 506:555-65. [PMID: 12613960 DOI: 10.1007/978-1-4615-0717-8_78] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- Ben J Glasgow
- Department of Ophthalmology, Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California, USA
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Glasgow BJ, Abduragimov AR, Gassymov OK, Yusifov TN, Ruth EC, Faull KF. Vitamin E associated with the lipocalin fraction of human tears. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 506:567-72. [PMID: 12613961 DOI: 10.1007/978-1-4615-0717-8_79] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Ben J Glasgow
- Department of Pathology and Ophthalmology, Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California, USA
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Glasson M, Stapleton F, Willcox M. Lipid, lipase and lipocalin differences between tolerant and intolerant contact lens wearers. Curr Eye Res 2002; 25:227-35. [PMID: 12658556 DOI: 10.1076/ceyr.25.4.227.13482] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Tear volume is reduced in symptomatic contact lens wearers, evaporation of the ocular tear film may be a cause. In this study we have focussed on symptomatic or intolerant subjects and compared their tear film lipid-related features to those tolerant to soft contact lens wear. METHOD Fourteen tolerant and 10 intolerant to lens wear subjects were recruited for this study. Intolerance to lens wear was defined as experiencing dryness symptoms in the first 6 hours of lens wear and consequently not being regular lens wearers. Lipid layer appearance was graded on a 0-5 scale, meibomian gland obstruction was observed, and the McMonnies questionnaire completed. Tears were collected without reflex stimulation. Degraded lipid (tear aldehyde content), secretory phospholipase A2 enzyme (sPLA2) concentration and activity and lipocalin concentration were analysed using spectrophotometry to quantify colour reactions and enzyme linked immunosorbent assays. Statistical results were calculated using non-parametric tests (median +/- interquartile range) or chi-squared test. RESULTS Degradation of polyunsaturated fatty acids and related esters leads to the by-products, malondialdehyde and 4-hydroxy-2(E)-nonenal. Intolerant subjects were found to have significantly (p = 0.004) higher concentrations of these by-products in their tears (0.85 +/- 1.0 microM; n = 9) compared to tolerant subjects (0.15 +/- 0.15 microM; n = 10). Intolerant subjects (1.86 +/- 0.05 ng/microl; n = 9) had significantly more (p = 0.047) sPLA2 enzyme in their tears compared with tolerant subjects (1.80 +/- 0.08 ng/microl; n = 12) and significantly more enzyme activity (p = 0.012). Intolerant subjects had significantly higher amounts of lipocalin in their tears (2.40 +/- 1.5 microg/microl; n = 10, p < 0.001) compared to tolerant subjects (0.45 +/- 0.85 microg/microl; n = 13). CONCLUSION Changes to the components of the tear film, however small, can disturb the nature and dynamics of the tear film. Increased lipases, degraded lipids and lipocalins in the aqueous tear film potentiates intolerance to contact lens wear and was associated with increased McMonnies dry eye history scores and symptoms scores.
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Affiliation(s)
- M Glasson
- Cooperative Research Centre for Eye Research and Technology, University of New South Wales, Kensington, Australia
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Abstract
Human tear prealbumin, now called tear lipocalin, was originally described as a major protein of human tear fluid, which was thought to be tear specific. However, recent investigations demonstrated that it is identical with lingual von Ebner's gland protein, and is also produced in prostate, nasal mucosa and tracheal mucosa. Homologous proteins have been found in rat, pig and probably dog and horse. Tear lipocalin is an unusual lipocalin member, because of its high promiscuity for relative insoluble lipids and binding characteristics that differ from other members. In addition, it shows inhibitory activity on cysteine proteinases similar to cystatins, a feature unique among lipocalins. Although it acts as the principal lipid binding protein in tear fluid, a more general physiological function has to be proposed due to its wide distribution and properties. It would be ideally suited for scavenging of lipophilic, potentially harmful substances and thus might act as a general protection factor of epithelia.
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Affiliation(s)
- B Redl
- Institut für Mikrobiologie, Medizinische Fakultät, Universität Innsbruck, Fritz Pregl Strasse 3, A-6020 Innsbruck, Austria.
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Gasymov OK, Abduragimov AR, Yusifov TN, Glasgow BJ. Binding studies of tear lipocalin: the role of the conserved tryptophan in maintaining structure, stability and ligand affinity. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1433:307-20. [PMID: 10515687 DOI: 10.1016/s0167-4838(99)00133-8] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The principal lipid binding protein in tears, tear lipocalin (TL), binds acid and the fluorescent fatty acid analogs, DAUDA and 16-AP at one site TL compete for this binding site. A fluorescent competitive binding assay revealed that apo-TL has a high affinity for phospholipids and stearic acid (Ki) of 1.2 microM and 1.3 microM, respectively, and much less affinity for cholesterol (Ki) of 15.9 of the hydrocarbon chain. TL binds most strongly the least soluble lipids permitting these lipids to exceed their maximum solubility in aqueous solution. These data implicate TL in solubilizing and transporting lipids in the tear film. Phenylalanine, tyrosine and cysteine+ were substituted for TRP 17, the only invariant residue throughout the lipocalin superfamily. Cysteine substitution resulted in some loss os secondary structure, relaxation of aromatic side chain rigidity, decreased binding affinity for DAUDA and destabilization of structure. Mutants of TL, W17Y, and W17F showed a higher binding affinity for DAUDA than wild-type TL. Comparison of the results of the tryptophan 17 substitution in lipocalin with those of tryptophan 19 substitution in beta-lactoglobulin revealed important differences in binding characteristics that reflect the functional heterogeneity within the lipocalin family.
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Affiliation(s)
- O K Gasymov
- Department of Pathology, UCLA School of Medicine, Jules Stein Eye Institute, 100 Stein Plaza, Los Angeles, CA 90095, USA
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Schoenwald RD, Vidvauns S, Wurster DE, Barfknecht CF. The role of tear proteins in tear film stability in the dry eye patient and in the rabbit. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 438:391-400. [PMID: 9634912 DOI: 10.1007/978-1-4615-5359-5_54] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- R D Schoenwald
- Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City, USA
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Ressot C, Lassagne H, Kemeny JL, Gachon AM. Tissue expression of tear lipocalin in humans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 438:69-73. [PMID: 9634865 DOI: 10.1007/978-1-4615-5359-5_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- C Ressot
- Laboratoire de Biochimie Médicale, Faculté de Médecine, Clermont-Ferrand Cedex, France
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Mathers WD, Lane JA. Meibomian gland lipids, evaporation, and tear film stability. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 438:349-60. [PMID: 9634908 DOI: 10.1007/978-1-4615-5359-5_50] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- W D Mathers
- University of Iowa Hospitals and Clinics, Department of Ophthalmology, Iowa City, USA
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Schoenwald RD, Vidvauns S, Wurster DE, Barfknecht CF. The influence of tear proteins on the film stability of rabbit tear extracts. J Ocul Pharmacol Ther 1998; 14:15-29. [PMID: 9493780 DOI: 10.1089/jop.1998.14.15] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This study was undertaken to gain an understanding of the significance of tear proteins in stabilizing the tear film. Either a sigma agonist, N,N-dimethyl-2-phenylethylamine HCl (AF2975), or a sigma antagonist, haloperidol, was administered to rabbit eyes in order to increase or decrease protein secretion, respectively. At 0, 10 and 60 minutes after instillation, tear proteins were extracted from Schirmer strips and measured for total protein. A portion of the extract was used for separating five major protein fractions using size-exclusion HPLC. Total protein extract or individual protein fractions were measured for surface tension by the horizontal capillary method and for in vitro break up time (in vitro BUT), a newly designed procedure. A statistically significant decrease was measured for surface tension and a concomitant increase was measured for in vitro BUT for the total protein samples at 10 and 60 minutes after instillation of AF2975 compared to the vehicle treated eye. The results for haloperidol yielded an increase in surface tension and an decrease in in vitro BUT. When the tear proteins were separated into five major fractions, only the 23 minute protein fraction was found to decrease surface tension and increase in vitro BUT following AF2975 administration. Haloperidol, a sigma antagonist, showed an exact opposite effect for the total protein and the 23 minute protein fraction.
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Affiliation(s)
- R D Schoenwald
- Division of Pharmaceutics, College of Pharmacy, The University of Iowa, Iowa City 52242, USA
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Molloy MP, Bolis S, Herbert BR, Ou K, Tyler MI, van Dyk DD, Willcox MD, Gooley AA, Williams KL, Morris CA, Walsh BJ. Establishment of the human reflex tear two-dimensional polyacrylamide gel electrophoresis reference map: new proteins of potential diagnostic value. Electrophoresis 1997; 18:2811-5. [PMID: 9504814 DOI: 10.1002/elps.1150181516] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To understand the changes in protein expression associated with various physiological states as well as the development of pathological eye disease, we have begun to map the protein components of normal human reflex tears. An analytical reference map of normal human reflex tears was created using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) with pH 3.5-10 immobilized pH gradients (IPGs). Micropreparatively loaded gels were transferred to polyvinylidene difluoride (PVDF) and analysed by a combination of N-terminal sequence tagging and amino acid compositional analysis. Thirty spots were sequence tagged, resulting in identification of six different proteins (lipocalin, lysozyme, lactotransferrin, zinc-alpha-2 glycoprotein, cystatin S, cystatin SN) that matched to entries in the SWISS-PROT database. A group of N-terminally blocked proteins was clearly identified from SWISS-PROT by amino acid analysis, isoelectric point (pI) and molecular weight (Mr). A number of highly expressed protein components remain unidentified despite being subjected to amino acid analysis and Edman sequencing. A majority of the abundant proteins showed varying degrees of charge heterogeneity attributed to post-translational processing such as glycosylation and N-terminal truncation. We have identified a previously undescribed protein that we have named lacryglobin. This protein displays strong homology with mammaglobin, a protein overexpressed in breast cancer. The discovery of this homologue in tears offers the potential for disease diagnosis by screening tear fluid proteins.
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Affiliation(s)
- M P Molloy
- Australian Proteome Analysis Facility, Macquarie University, Sydney
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Baeyens V, Gurny R. Chemical and physical parameters of tears relevant for the design of ocular drug delivery formulations. PHARMACEUTICA ACTA HELVETIAE 1997; 72:191-202. [PMID: 9372641 DOI: 10.1016/s0031-6865(97)00021-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This paper provides a summary of the most important chemical and physical parameters of tears that can help the formulator in the development of new ocular formulations and in the conception of innovative ophthalmic delivery approaches. For each physiological parameter, the relevance in ocular drug delivery is discussed in detail and the analytical tools that are used for the determination of these parameters are described and summarized. The aim of this review is also to give a description of the main analytical techniques available in ophthalmology that can be used for pharmacokinetic studies of active compounds. The importance of tear sampling techniques used in the determination of the parameters is also discussed.
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Affiliation(s)
- V Baeyens
- School of Pharmacy, University of Geneva, Switzerland
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Glasgow BJ, Abduragimov AR, Farahbakhsh ZT, Faull KF, Hubbell WL. Tear lipocalins bind a broad array of lipid ligands. Curr Eye Res 1995; 14:363-72. [PMID: 7648862 DOI: 10.3109/02713689508999934] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To identify the native ligands of tear lipocalins, tear proteins were separated by size exclusion chromatography and the lipid content in the major protein fractions identified. Lipids extracted from native tears and purified tear lipocalins comigrated with fatty acids, fatty alcohols, phospholipids, glycolipids, and cholesterol on thin layer chromatograms. Abundant stearic and palmitic acids as well as cholesterol, and lesser amounts of lauric acid were specifically identified in extracts of purified lipocalins by gas chromatography-mass spectroscopy. A preliminary study of the ligand-protein interaction was carried out using nitroxide spin-labeled lipids.
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Affiliation(s)
- B J Glasgow
- Department of Ophthalmology, UCLA School of Medicine 90024, USA
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Kijlstra A, Kuizenga A. Analysis and function of the human tear proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 350:299-308. [PMID: 8030492 DOI: 10.1007/978-1-4615-2417-5_51] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- A Kijlstra
- Graduate School Neurosciences Amsterdam, The Netherlands Ophthalmic Research Institute
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Gachon AM. Human lacrimal gland secretes proteins belonging to the group of hydrophobic molecule transporters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 350:205-10. [PMID: 8030478 DOI: 10.1007/978-1-4615-2417-5_36] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- A M Gachon
- Laboratoire de Biochimie Médicale, Faculté de Médecine, Clermont-Ferrand, France
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Claudon-Eyl V, Baguet J. Electrophoretic patterns of human denatured tear proteins and glycoproteins from normal subjects and soft contact lens wearers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 350:411-6. [PMID: 8030510 DOI: 10.1007/978-1-4615-2417-5_71] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- V Claudon-Eyl
- Laboratoire Meuse Optique Contact (MOC), Centre Hospitalier Bar le Duc, France
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Glasgow BJ, Heinzmann C, Kojis T, Sparkes RS, Mohandas T, Bateman JB. Assignment of tear lipocalin gene to human chromosome 9q34-9qter. Curr Eye Res 1993; 12:1019-23. [PMID: 8306712 DOI: 10.3109/02713689309029229] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We assigned the gene for tear lipocalin to the long arm of human chromosome 9. Polyadenylated RNA was extracted from lacrimal gland. The coding region for tear lipocalin was amplified, sequenced and used to probe a panel of somatic cell hybrid DNA by Southern blot analysis. Regional mapping was accomplished by probing a panel of subfragments of the indicated chromosome. Restriction of genomic DNA with EcoRI failed to reveal any bands corresponding to the human tear lipocalin gene in mouse-human hybrids all of which lack chromosome 9. Southern blot analysis of human-hamster hybrids demonstrated a human 5.6 kb TaqI restriction fragment that segregated to the q34-qter region of chromosome 9 and assigned the gene for tear lipocalin to this region. Structurally homologous proteins of the lipocalin family, human placental protein 14, human alpha 1 microglobulin, and human brain prostaglandin synthase, have been mapped to this region. We suggest that the gene for tear lipocalin is part of an important lipocalin superfamily gene cluster on chromosome 9 within band q34.
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Affiliation(s)
- B J Glasgow
- Department of Ophthalmology, Jules Stein Eye Institute, UCLA School of Medicine 90024
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Bodelier VMW, van Haeringen NJ, Klaver PSY. Species differences in tears; Comparative investigation in the chimpanzee (Pan troglodytes). Primates 1993. [DOI: 10.1007/bf02381283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Baguet J, Claudon-Eyl V, Gachon AM. Tear protein G originates from denatured tear specific prealbumin as revealed by two-dimensional electrophoresis. Curr Eye Res 1992; 11:1057-65. [PMID: 1483336 DOI: 10.3109/02713689209015077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
One-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D-SDS PAGE) of the non-denatured low molecular weight (MW) tear proteins (dilution in phosphate buffered saline or in the non-ionic detergent Triton X100) revealed no protein G but a strongly marked 23-kD related to a tear specific prealbumin (TSP) subunit coming with the known 15, 17, 18 and 20-kD TSP subunits. Under mild denaturating conditions of sample preparation with SDS dilution just before electrophoresis, 23-kD protein decreased and a faint 32-kD protein G appeared. Under stronger denaturing conditions of sample preparation with SDS treatment (boiling or freeze-thaw cycles), 23-kD protein disappeared and two main protein G forms (32 and 34-kD) and additional bands (29, 36, 39, 42, 57 and 60-kD) appeared depending on the sample treatment. The isoelectric pH (pI) of these proteins ranged from pH 5.2 to pH 5.4. Different two-dimensional electrophoresis methods revealed that: - in presence of SDS, 23-kD protein was spontaneously changed into 17-kD TSP and such a phenomenon was partially reversible by using a non-ionic detergent (Triton X100), new proteins appeared under denaturating processes were related to various protein G forms and originated from TSP group, proteins G were produced by the aggregation of TSP subunit related to MW 17-kD/pI 5.0 corresponding to the major TSP subunit, disulfide bond formation was shown to play a major role in the aggregation process although protein G group was not totally reduced by dithiothreitol. Such results suggest that protein G is an in vitro experimental artifact due to denaturing conditions with SDS treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Baguet
- Laboratoire Meuse Optique Contact (MOC), Centre Hospitalier, Bar le Duc, France
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