Aim: To determine the expression and distribution of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in the normal human iris and ciliary body. Methods: Seven postmortem human eyes were fixed with formalin. The iris and ciliary body were dissected out and embedded in paraffin. The expression of MMPs -1, 2, 3, and 9, and TIMPs 1-4 in the iris and ciliary body was determined by a novel immunofluorescence technique and the results graded by masked observers. Results: Positive staining for MMPs and TIMPs was observed in all regions of the anterior uvea, and was more intense in the ciliary body than in the iris. Most MMPs and TIMPs showed similar patterns in their distribution. In the ciliary body, staining was strongest in the epithelium, and was localised to the epithelial cell cytoplasm, except for TIMP-3 which was strongly expressed in the basement membranes. In the iris, staining was most noticeable in the anterior border and anterior epithelial layer. Blood vessels in the stroma of the iris and ciliary body also stained moderately for MMPs and TIMPs. Conclusion: Both MMPs and TIMPs are widely expressed in the anterior uvea, with a positive correlation between their expressions. Their differential localisation in the ciliary body suggests they may have a role in maintaining homeostasis in the uveal tract.
INTRODUCTION: Secretory immunoglobulin A (sIgA) is the predominant immunoglobulin in tears. The role of sIgA in defending the eye against pathogens has not been established clearly. There have been conflicting reports about the effect of contact lens wear on the concentration of sIgA in tears. This study was conducted to elucidate the role of sIgA in ocular defence and to determine the effect of contact lens wear on sIgA concentration. METHODS: Tears were collected from contact lens wearers and non-wearers using micro-capillary tubes. The concentration of sIgA was evaluated using an in-house ELISA. The specificity of sIgA to a strain of P. aeruginosa was examined using a fluorescent assay and the ability of neutrophils to phagocytose sIgA coated bacteria were assessed by plate counts. RESULTS: Tears contained sIgA that reacted to P. aeruginosa. P. aeruginosa coated with sIgA was phagocytosed by the neutrophils. The level of sIgA and the level of sIgA specific to P. aeruginosa in the tears of contact lens wearers were significantly reduced. CONCLUSIONS: These results indicate that contact lens wear significantly alters the level of sIgA in tears which may lead to changes in the ability of the ocular surface to defend itself against potential pathogens.
Bacterial pathogens are often involved in contact lens-related adverse responses. This study aimed to find antimicrobial peptides and proteins that effectively eradicate or inhibit ocular bacteria. The antimicrobials were screened against gram-negative and gram-positive bacteria originating from ocular sources. The viability of these ocular bacteria was measured after exposure to the peptides and proteins. Two conditions were used to grow bacteria, low nutrient phosphate-buffered saline and high nutrient tryptone soya broth. Samples were taken at different times up to 48 h. In low nutrient conditions, protamine was found to be the most effective against all strains. Melittin was very effectve against all strains except Serratia and one Pseudomonas isolate which were partially affected. In high nutrient condition, only melittin was effective in killing Staphylococcus aureus. Protamine and the combination of protamine and melittin had the greatest effect in eradicating the bacteria tested in low nutrient condition. Protamine alone and its combination with melittin may have potential therapeutic agents for ocular infections in an era of emerging antibiotic resistance.
The massive recruitment of PMN in tears during sleep may be partially attributed to the increased levels of tear sIgA. This may play an important role in protecting the eye against bacterial infection.
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