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Khan M, Stapleton F, Willcox MDP. Susceptibility of Contact Lens-Related Pseudomonas aeruginosa Keratitis Isolates to Multipurpose Disinfecting Solutions, Disinfectants, and Antibiotics. Transl Vis Sci Technol 2020; 9:2. [PMID: 32821474 PMCID: PMC7401903 DOI: 10.1167/tvst.9.5.2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 12/29/2019] [Indexed: 12/17/2022] Open
Abstract
Purpose This study analyzed the susceptibilities of 17 contact lens (CL)-related keratitis isolates of Pseudomonas aeruginosa from Australia to antibiotics, multipurpose contact lens disinfecting solutions (MPDS), and disinfectants through minimum inhibitory (MIC) and minimum bactericidal concentrations. Methods Antibiotics included ciprofloxacin, levofloxacin, gentamicin, tobramycin, piperacillin, imipenem, ceftazidime, and polymyxin B. The MPDS OPTI-FREE PureMoist, Complete RevitaLens OcuTec, Biotrue, and Renu Advanced Formula and the constituent disinfectants; alexidine dihydrochloride, polyquaternium-1, polyaminopropyl biguanide, and myristamidopropyl dimethylamine (Aldox) were analyzed. The combined susceptibility of disinfectants based on the MPDS formulation was assessed through fractional inhibitory concentration. Results All isolates were susceptible to levofloxacin and gentamicin, 2/17 were resistant to ciprofloxacin; 1/17 was resistant to tobramycin, piperacillin, and polymyxin; and 3/17 were resistant to ceftazidime whereas 12/17 were resistant to imipenem. Of the four MPDSs, for Renu Advanced Formula 8/17 strains have an MIC ≤ 11.36 for OPTI-FREE PureMoist 14/17 strains have an MIC ≤ 11.36% for Complete RevitaLens 9/17 strains have an MIC ≤ 11.36, and for Biotrue 5/17 strains have MIC = 11.36. All strains were killed by 100% MPDS. At the concentrations used in the MPDSs, individual disinfectants were not active. From three tested isolates, no synergy was found in dual combinations of disinfectants. However, synergy was found for triple combination of disinfectants for three tested strains. Conclusions Australian CL-related isolates of P aeruginosa were susceptible to most antibiotics. There was variability in susceptibility to different MPDS. Individual disinfectant excipients had limited activity. The combination of the disinfectants showed synergy, antagonism, and no interaction. Translational Relevance This study will help to choose better preventive and treatment measures for microbial keratitis.
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Affiliation(s)
- Mahjabeen Khan
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Fiona Stapleton
- School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
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Yasir M, Willcox MDP, Dutta D. Action of Antimicrobial Peptides against Bacterial Biofilms. Materials (Basel) 2018; 11:ma11122468. [PMID: 30563067 PMCID: PMC6317029 DOI: 10.3390/ma11122468] [Citation(s) in RCA: 151] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/22/2022]
Abstract
Microbes are known to colonize surfaces and form biofilms. These biofilms are communities of microbes encased in a self-produced matrix that often contains polysaccharides, DNA and proteins. Antimicrobial peptides (AMPs) have been used to control the formation and to eradicate mature biofilms. Naturally occurring or synthetic antimicrobial peptides have been shown to prevent microbial colonization of surfaces, to kill bacteria in biofilms and to disrupt the biofilm structure. This review systemically analyzed published data since 1970 to summarize the possible anti-biofilm mechanisms of AMPs. One hundred and sixty-two published reports were initially selected for this review following searches using the criteria ‘antimicrobial peptide’ OR ‘peptide’ AND ‘mechanism of action’ AND ‘biofilm’ OR ‘antibiofilm’ in the databases PubMed; Scopus; Web of Science; MEDLINE; and Cochrane Library. Studies that investigated anti-biofilm activities without describing the possible mechanisms were removed from the analysis. A total of 17 original reports were included which have articulated the mechanism of antimicrobial action of AMPs against biofilms. The major anti-biofilm mechanisms of antimicrobial peptides are: (1) disruption or degradation of the membrane potential of biofilm embedded cells; (2) interruption of bacterial cell signaling systems; (3) degradation of the polysaccharide and biofilm matrix; (4) inhibition of the alarmone system to avoid the bacterial stringent response; (5) downregulation of genes responsible for biofilm formation and transportation of binding proteins.
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Affiliation(s)
- Muhammad Yasir
- School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia.
| | | | - Debarun Dutta
- School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia.
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Yerramothu P, Vijay AK, Willcox MDP. Inflammasomes, the eye and anti-inflammasome therapy. Eye (Lond) 2017; 32:491-505. [PMID: 29171506 DOI: 10.1038/eye.2017.241] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 08/28/2017] [Indexed: 02/08/2023] Open
Abstract
Inflammasomes, key molecular regulators that play an important role in inflammation, consist of a central protein, an adaptor protein ASC (apoptosis speck-like protein) and a caspase-1 protein. Upon activation, caspase-1 induces maturation of cytokines such as interleukin-1β (IL-1β) and interleukin-18 (IL-18). The release of these cytokines can result in inflammation. Inflammasomes are activated by a variety of factors and their activation involves complex signalling leading to resolution of infection, but can also contribute to the pathology of inflammatory, autoimmune, and infectious diseases. The role of NLRP1, NLRP3, NLRC4 and AIM2 inflammasomes in the pathogenesis of ocular diseases such as glaucoma, age related macular degeneration (AMD), diabetic retinopathy, dry eye and infections of the eye has been established over the past decade. In experimental studies and models, inhibition of inflammasomes generally helps to reduce the inflammation associated with these eye diseases, but as yet the role of these inflammasomes in many human eye diseases is unknown. Therefore, a need exists to study and understand various aspects of inflammasomes and their contribution to the pathology of human eye diseases. The goal of this review is to discuss the role of inflammasomes in the pathology of eye diseases, scope for anti-inflammasome therapy, and current research gaps in inflammasome-related eye disease.
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Affiliation(s)
- P Yerramothu
- School of Optometry and Vision Science, Faculty of Science, University of New South Wales, Sydney, Australia
| | - A K Vijay
- School of Optometry and Vision Science, Faculty of Science, University of New South Wales, Sydney, Australia
| | - M D P Willcox
- School of Optometry and Vision Science, Faculty of Science, University of New South Wales, Sydney, Australia
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Abstract
PURPOSE To investigate the expression of proteases, proteolytic activity and cytokines in the tear film of people with keratoconus. METHODS Basal tears from people with keratoconus, from individuals who had undergone corneal collagen cross-linking for the treatment of keratoconus, and from normal controls were collected using a capillary tube. Corneal curvature of each subject was mapped. The total protein in tears was estimated. Levels and activity of proteases in the tears were analysed using specific antibody arrays and activity assays. RESULTS The total tear protein level was significantly reduced in keratoconus (4.1 ± 0.9 mg/ml) compared with normals (6.7 ± 1.4 mg/ml) (p < 0.0001) or subjects who had undergone corneal collagen cross-linking (5.7 ± 2.3 mg/ml) (p < 0.005). Significantly (p < 0.05) increased tear expression of matrix metalloproteinases (MMP) -1, -3, -7, -13, interleukins (IL) -4, -5, -6, -8 and tumour necrosis factor (TNF) -α, -β were evident in keratoconus. Tear IL-6 was the only cytokine significantly (p < 0.05) increased in tears of keratoconus subjects compared with the collagen cross-linked group. No significant difference in tear proteases were observed between the normal and the cross-linked groups, although the expression of TNF-α was significantly (p < 0.05) increased in the cross-linked group compared with the controls. Elevated gelatinolytic (87.5 ± 33.6 versus 45.8 ± 24.6 FIU, p < 0.0001) and collagenolytic (6.1 ± 3.2 versus 3.6 ± 2.0 FIU, p < 0.05) activities were observed in tears from keratoconus compared with normal subjects. The activity of tear gelatinases (69.6 ± 22.2 FIU) and collagenases (5.7 ± 3.3 FIU) in the collagen cross-linked group was not significantly different compared with either keratoconus or normals. CONCLUSION Tears of people with keratoconus had 1.9 times higher levels of proteolytic activity and over expression of several MMPs and cytokines compared with tears from controls. Further investigations are required to study the possible implications of these changes and whether they can be used to monitor disease progression or determine the success of corneal collagen cross-linking.
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Balasubramanian SA, Pye DC, Willcox MDP. Levels of lactoferrin, secretory IgA and serum albumin in the tear film of people with keratoconus. Exp Eye Res 2012; 96:132-7. [DOI: 10.1016/j.exer.2011.12.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 12/05/2011] [Accepted: 12/10/2011] [Indexed: 12/27/2022]
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Rasul R, Cole N, Balasubramanian D, Chen R, Kumar N, Willcox MDP. Interaction of the antimicrobial peptide melimine with bacterial membranes. Int J Antimicrob Agents 2010; 35:566-72. [PMID: 20227248 DOI: 10.1016/j.ijantimicag.2010.02.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 02/02/2010] [Accepted: 02/04/2010] [Indexed: 11/26/2022]
Abstract
Melimine is a novel cationic peptide possessing broad-spectrum antimicrobial activity that is retained when attached to a surface, suggesting that interactions with bacterial membranes may be of primary importance to its activity. The effects of alterations in the environment on the conformation of melimine were investigated using circular dichroism and fluorescence spectra in membrane-mimetic solvents. Furthermore, the interactions of melimine with bacterial membranes of Pseudomonas aeruginosa and Staphylococcus aureus were examined using scanning electron and fluorescence microscopy, and perturbation of membrane integrity was tested by measurement of melimine-mediated diSC(3)-5 dye release from bacterial cells. Melimine has a predominantly random coil conformation that adopts a helical fold when exposed to organic solvents. However, when it is solubilised in micelles of sodium dodecyl sulphate, which are bacterial membrane-mimetic, the alpha-helical content increases to ca. 35-40%. A major effect of melimine was on the integrity of the cytoplasmic membrane both for P. aeruginosa and S. aureus. However, for P. aeruginosa the rapid loss of cytoplasmic membrane integrity correlated directly with loss of cell viability, whilst for S. aureus maximal dye release was obtained at concentrations where there was no significant loss of viability. There have been few studies to date investigating differences in the action of cationic peptides towards Gram-positive and Gram-negative bacteria. Consequently, further investigation of these mechanistic differences may allow more refined targeting of increasingly difficult-to-treat bacterial infections and/or further inform design of novel peptides with improved broad-spectrum activity.
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Affiliation(s)
- R Rasul
- Institute for Eye Research, The University of New South Wales (UNSW), Sydney, NSW 2052, Australia
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Glasson MJ, Stapleton F, Keay L, Willcox MDP. The effect of short term contact lens wear on the tear film and ocular surface characteristics of tolerant and intolerant wearers. Cont Lens Anterior Eye 2006; 29:41-7; quiz 49. [PMID: 16497539 DOI: 10.1016/j.clae.2005.12.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 12/01/2005] [Accepted: 12/22/2005] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to determine the effect of contact lens wear on the tear film and ocular surface of people tolerant or intolerant to contact lens wear. Twenty subjects participated; 11 tolerants and nine intolerants. Their baseline tear film (no lens wear) was analysed with a range of clinical measurements and protein analyses (lactoferrin, sIgA and lysozyme). The tests were then repeated at the end of 6h of contact lens wear during the day and while lenses were worn. Both tolerants and intolerants showed statistically significant increases in bulbar and overall conjunctival redness after 6h of lens wear. For tolerants only, there was a statistically significant increase in the tear film meniscus area (0.08 mm(2) +/- 0.04 compared to 0.14 mm(2) +/- 0.06 (p = 0.023)) and a statistically significant decrease in the non-invasive tear film break-up time (NI-TBUT; 21.3 s +/- 5.7 compared to 3.7 s +/- 4.3 (p = 0.003)) after 6h of lens wear. There were no changes in other tear film or ocular surface parameters. The protein concentration and lipid layer appearance did not change during lens wear for either population. Prior to lens wear, tolerant subjects had a statistically longer NI-TBUT, higher phenol red thread test and higher tear flow rate. After 6h of lens wear and while wearing lenses, all but NI-TBUT remained statistically different. Lens wear affected only a small number of clinical variables and 6h wear did not effect the concentration of those proteins measured in tears in this study.
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Bandara BMK, Sankaridurg PR, Willcox MDP. Non-steroidal anti inflammatory agents decrease bacterial colonisation of contact lenses and prevent adhesion to human corneal epithelial cells. Curr Eye Res 2005; 29:245-51. [PMID: 15590469 DOI: 10.1080/02713680490516729] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE To investigate non-steroidal anti-inflammatory agents (NSAIDs), salicylic acid, sodium diclofenac and ketorolac for inhibition of bacterial colonization of contact lenses (CL) and human corneal epithelial cells (HCE). METHODS CLs pre-colonised with Pseudomonas aeruginosa, Haemophilus influenzae, Staphylococcus epidermidis and Streptococcus pneumoniae were exposed overnight to NSAIDs and the number of viable bacteria on the CLs were calculated. Cytotoxicity of NSAIDs to HCE cells was evaluated with the MTT assay. Viable counts were used to measure the adhesion of P. aeruginosa and S. epidermidis to HCE cells in the presence of the least cytotoxic NSAID. RESULTS All NSAIDs significantly decreased bacterial colonization of CLs in a dose-dependent manner. Salicylic acid (100 mM) completely inhibited colonisation of all species tested and was the least cytotoxic. Salicylic acid also prevented adhesion of P. aeruginosa and S. epidermidis to HCE (60% and 58% inhibition at 60 mM at 2 hours). CONCLUSIONS Salicylic acid demonstrated potential as a compound for incorporation into anti-bacterial strategies to prevent bacterial contamination of contact lenses. This study highlighted the potential for NSAIDs as anti-bacterial agents and indicates that this class of compound should be investigated for other suitable candidates.
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Affiliation(s)
- B M K Bandara
- Co-operative Research Centre for Eye Research and Technology, Sydney, NSW 2052, Australia
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Hume EBH, Baveja J, Muir B, Schubert TL, Kumar N, Kjelleberg S, Griesser HJ, Thissen H, Read R, Poole-Warren LA, Schindhelm K, Willcox MDP. The control of Staphylococcus epidermidis biofilm formation and in vivo infection rates by covalently bound furanones. Biomaterials 2004; 25:5023-30. [PMID: 15109864 DOI: 10.1016/j.biomaterials.2004.01.048] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2001] [Accepted: 01/20/2004] [Indexed: 11/28/2022]
Abstract
In order to overcome the continuing infection rate associated with biomaterials, the use of covalently bound furanones as an antibiofilm coating for biomaterials has been investigated. Furanones have previously been shown to inhibit growth of Gram-positive and Gram-negative bacteria. The aim of these studies were to covalently bind furanones to polymers and to test their efficacy for inhibiting biofilm formation of Staphylococcus epidermidis and in vivo infection rate. Two methods of covalent attachment of furanones were used. The first, a co-polymerisation with a styrene polymer, and second, a plasma-1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC) reaction to produce furanone-coated catheters. Biofilm formation by S. epidermidis in vitro was inhibited by 89% for polystryene-furanone disks and by 78% by furanone-coated catheters (p<0.01). In an in vivo sheep model we found furanones were effective at controlling infection for up to 65 days. Furanones have potential to be used as a coating for biomaterials to control infection caused by S. epidermidis.
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Affiliation(s)
- E B H Hume
- Cooperative Research Centre for Eye Research and Technology, Vision CRC, The University of New South Wales, Sydney, NSW 2052, Australia
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Baveja JK, Willcox MDP, Hume EBH, Kumar N, Odell R, Poole-Warren LA. Furanones as potential anti-bacterial coatings on biomaterials. Biomaterials 2004; 25:5003-12. [PMID: 15109862 DOI: 10.1016/j.biomaterials.2004.02.051] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Accepted: 05/13/2003] [Indexed: 11/26/2022]
Abstract
A major barrier to the long-term use of medical devices is development of infection. Staphylococcus epidermidis is one of the most common bacterial isolates from these infections with biofilm formation being their main virulence factor. Currently, antibiotics are used as the main form of therapy. However with the emergence of staphylococcal resistance, this form of therapy is fast becoming ineffective. In this study, the ability of a novel furanone antimicrobial compound to inhibit S. epidermidis adhesion and slime production on biomaterials was assessed. Furanones were physically adsorbed to various biomaterials and bacterial load determined using radioactivity. Slime production was assessed using a colorimetric method. Additionally, the effect of the furanone coating on material surface characteristics such as hydrophobicity and surface roughness was also investigated. The results of this study indicated that there was no significant change in the material characteristics after furanone coating. Bacterial load on all furanone-coated materials was significantly reduced (p<0.001) as was slime production (p<0.001). There is a potential for furanone-coated biomaterials to be used to reduce medical device-associated infections.
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Affiliation(s)
- J K Baveja
- Cooperative Research Centre for Eye Research and Technology, University of New South Wales, Sydney, NSW 2052, Australia
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Baveja JK, Li G, Nordon RE, Hume EBH, Kumar N, Willcox MDP, Poole-Warren LA. Biological performance of a novel synthetic furanone-based antimicrobial. Biomaterials 2004; 25:5013-21. [PMID: 15109863 DOI: 10.1016/j.biomaterials.2004.02.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Accepted: 02/02/2004] [Indexed: 10/26/2022]
Abstract
Infection of medical devices causes significant morbidity and mortality and considerable research effort has been directed at solving this problem. The aim of this study was to assess the biological performance of a novel furanone compound that has potential as an anti-infective coating for medical devices. This study examined in vitro leukocyte response following exposure to the antibacterial 3-(1'-bromohexyl)-5-dibromomethylene-2(5H)-furanone and assessed the tissue response following subcutaneous implantation of the furanone compound covalently bound to polystyrene (PS). Peripheral human blood was exposed to furanones in solution for 1h and flow cytometry used to analyse viability and changes in expression of surface receptors CD11b/CD18 and CD44. Flow cytometry results from propidium iodide stained cell suspensions suggested that the leukocytes were viable after exposure to furanones in whole blood. No significant difference was found in the expression of CD11b/CD18 and CD44 between the furanone exposed samples and the negative control for neutrophils suggesting that the furanones themselves do not activate these leukocytes. The positive control lipopolysaccharide significantly up-regulated CD11b/CD18 and slightly down-regulated CD44 on both PMNs and monocytes. In vivo studies of the tissue response to furanone covalently bound to PS showed that there was no significant difference in cellularity of capsules surrounding the disk and no significant increase in myeloperoxidase expression. These results demonstrate negligible acute inflammatory response to synthetic brominated antibacterial furanones. Future studies will focus on chronic responses and examination of in vivo efficacy.
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Affiliation(s)
- J K Baveja
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney NSW 2052, Australia
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Hume EBH, Willcox MDP. Emergence of Serratia marcescens as an ocular surface pathogen. Arch Soc Esp Oftalmol 2004; 79:475-7. [PMID: 15523567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
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Abstract
The aim of this study was to elucidate the expression of chemokines, their role and regulation in bacterial corneal infection using three bacterial strains (Pseudomonas. aeruginosa- invasive, cytotoxic and contact lens induced acute red eye strains) which have been shown to produce three distinct patterns of corneal disease in the mouse. The predominant chemokine expressed in response to all three strains was MIP-2. Prolonged expression of high levels of MIP-2 was associated with increased severity of corneal inflammation. Significantly reduced disease severity upon administration of anti-MIP-2 antibodies suggested that MIP-2 may play an important role in the pathogenesis of Pseudomonas keratitis at least in part by being a major chemoattractant for polymorphonuclear leukocytes (PMN) recruitment. Interestingly, the numbers of bacteria in eyes with neutralized MIP-2 activity did not decrease even though the severity of the disease was decreased. This implies PMNs as the major destructive factor in microbial keratitis. Further, neutralization of IL-1beta activity alone using monoclonal antibodies resulted in significant reduction of both MIP-2 and KC activity indicating that chemokine levels were regulated by IL-1beta. These studies demonstrate that the regulation of MIP-2 activity may be beneficial in reducing corneal damage during microbial keratitis in rodents and perhaps that regulation of the human homologue of MIP-2, IL-8, may be useful for controlling keratitis in humans.
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Affiliation(s)
- M L Xue
- Cooperative Research Centre for Eye Research and Technology, Cornea and Contact Lens Research Unit, The University of New South Wales, Sydney, NSW 2052, Australia
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Abstract
PURPOSE Contact lens-induced peripheral ulceration (CLPU) is a relatively common adverse response associated with wearing hydrogel lenses, especially on an extended wear schedule. Bacteriologic examination of lenses at the time of an event has demonstrated an association with Staphylococci spp. We sought to investigate the causes of CLPU in a rabbit model of contact lens wear. METHODS Rabbits wore contact lenses for a period of 24 hr in the presence or absence of bacteria or in presence or absence of epithelial scratches made in the periphery of the cornea before lens wear. Bacteria tested were a strain of Staphylococcus aureus or a strain of Staphylococcus epidermidis isolated from human CLPUs. Rabbits were also challenged with S. aureus in the presence of an epithelial defect and in the absence of a contact lens. Corneas were monitored by slitlamp, histology, and microbial culture after 24 hr. RESULTS No CLPU-like lesions were detected under the following conditions: corneal scratch plus lens wear with no bacteria; corneal scratch plus S. epidermidis colonized lenses; corneal scratch without lens wear and with S. aureus applied to eyes; no scratch plus S. aureus colonized lenses; and corneal scratch plus contact lenses colonized by dead S. aureus. CLPU-like lesions were found only when the corneas were scratched and contact lenses colonized by viable S. aureus were applied to the eye. The histology of the lesions demonstrated a frank epithelial break with underlying stromal infiltration. Only low numbers of bacteria could be cultivated from the corneas with CLPU-like lesions. The CLPU-like lesions shared many similarities with CLPU in humans. CONCLUSION CLPU-like lesions were only produced by S. aureus and not S. epidermidis in the presence of an epithelial abrasion and contact lens. Thus, we hypothesize that to reduce the incidence of CLPU, contact lenses designed to reduce corneal interaction and repel microbial colonization should be produced.
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Affiliation(s)
- P Wu
- Cooperative Research Centre for Eye Research and Technology, University of New South Wales, Sydney, Australia
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Thakur A, Xue M, Stapleton F, Lloyd AR, Wakefield D, Willcox MDP. Balance of pro- and anti-inflammatory cytokines correlates with outcome of acute experimental Pseudomonas aeruginosa keratitis. Infect Immun 2002; 70:2187-97. [PMID: 11895986 PMCID: PMC127830 DOI: 10.1128/iai.70.4.2187-2197.2002] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The purpose of this study was to elucidate the expression of pro- and anti-inflammatory cytokines in mouse corneas infected with Pseudomonas aeruginosa. Three bacterial strains (invasive, cytotoxic, or CLARE [contact lens-induced acute red eye]) which have recently been shown to produce distinct patterns of corneal disease in the mouse were used. The left mouse (BALB/c) corneas were scarified and infected with 2 x 10(6) CFU of one of the three P. aeruginosa strains, while right eyes served as controls. Animals were examined at 1, 4, 8, 16, and 24 h with a slit lamp biomicroscope to grade the severity of infection. Following examination, eyes were collected and processed for histopathology, multiprobe RNase protection assay for cytokine mRNA, enzyme-linked immunosorbent assay to quantitate cytokine proteins, and myeloperoxidase activity to quantitate polymorphonuclear leukocytes. The kinetics of appearance and magnitude of expression of key cytokines varied significantly in the three different phenotypes of P. aeruginosa infection. The predominant cytokines expressed in response to all three phenotypes were interleukin-1 beta (IL-1 beta), IL-1Ra, and IL-6. In response to the invasive strain, which induced severe corneal inflammation, significantly lower ratios of IL-1Ra to IL-1 beta were present at all time points, whereas corneas challenged with the CLARE strain, which induced very mild inflammation, showed a high ratio of IL-1Ra to IL-1 beta. The outcome of infection in bacterial keratitis correlated with the relative induction of these pro- and anti-inflammatory cytokines, and exogenous administration of recombinant rIL-1Ra (rIL-1Ra) was able to reduce the disease severity significantly. These findings point to the therapeutic potential of rIL-1Ra protein in possible treatment strategies for bacterial keratitis.
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Affiliation(s)
- A Thakur
- Cornea and Contact Lens Research Unit, Cooperative Research Centre for Eye Research and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia.
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Abstract
The cationic tear proteins lactoferrin and lysozyme exhibit co-operative antistaphylococcal properties. The purpose of this study was to determine the mechanism of action of this co-operation on Staphylococcus epidermidis. Following blocking of lipoteichoic acid (LTA) binding sites, the effects on binding of lactoferrin and susceptibility to lactoferrin and lysozyme were determined. The effect of lactoferrin on autolysis and LTA release was also examined. Maximal susceptibility occurred on addition of lactoferrin first followed by lysozyme. Blocking the LTA binding sites both reduced lactoferrin binding and decreased susceptibility. Autolytic activity decreased and LTA release increased in the presence of lactoferrin. These results suggest that binding of lactoferrin to LTA is important in its synergy with lysozyme and interferes with the autolysins present on the LTA. It is proposed that, on binding to the anionic LTA of S. epidermidis, the cationic protein lactoferrin decreases the negative charge, allowing greater accessibility of lysozyme to the underlying peptidoglycan.
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Affiliation(s)
- E C Leitch
- Cooperative Research Centre for Eye Research and Technology, University of New South Wales, 22-32 King Street, Randwick 2031, NSW, Australia
| | - M D P Willcox
- Cooperative Research Centre for Eye Research and Technology, University of New South Wales, 22-32 King Street, Randwick 2031, NSW, Australia
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