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Graham R Wallace, Matthew Davidson, Mariam Murad, Mohith Shamdas, Saaeha Rauz; Ocular eye drop preparations inhibit neutrophil extracellular trap formation. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6720.
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© ARVO (1962-2015); The Authors (2016-present)
Dry eye disease (DED) is a multifactorial disorder of the ocular surface characterised by tear film instability, hyperosmolarity and inflammation. Topically applied artificial tear substitutes are the mainstay treatment for DED providing lubrication between the palpebral conjunctiva and ocular surface, they provide effective symptom relief however are not ideal therapeutic agents. Neutrophils are present in the tear film of patients with moderate to severe dry eye disease. NETs have been localised to the corneas of healthy controls and patients with dry eye. The aim of this study was to analyse the effect of commercial eye drops on neutrophil function
Blood was collected from healthy volunteers in heparinised vacutainers and was processedwithin one hour of collection. Neutrophils were separated by Dextran centrifugation . 2x105 cells were added to coverslips in 24 well plate and stimulated with Phorbol 12-myristate 13-acetate (PMA) or formyl-Met-Leu-Phe (fMLP). Commercial topical eye drops were added to appropriate wells at 50% concentration. NETs were visualised by Sytox Green staining and ImageJ. Reactive oxygen species (ROS) production was measured by a commercial kit
Of the topical eye drops tested most had no effect on neutrophil NETosis in response to PMA. However two preparations Optimel Manuka Dry Eye drops and ThealozDuo eye drops significantly inhibited NET production in a dose dependent manner. Optimel drops were not cytotoxic to neutrophils at any of the concentrations tested therefore were inducing a more intrinsic effect on the cells. Optimel, but not Thealoz-Duo drops, significantly reduced ROS production a process which is strongly associated with NETosis. Thealoz-Duo do not kill PMN directly, but the mechanism by which NETosis is inhibited is not clear.
It is proposed that a reduction in NETosis at the ocular surface in the context of dry eye disease would be beneficial. However, NETs have also been reported to cause tissue damage and this may propagate epithelial layer damage. While NETosis was inhibited, neither eye drop preparation affected neutrophil survival, and though ROS production was significantly affected, a combination of active neutrophils that do not produce NETs may provide a protective cell population in dry eye disease.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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