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Malia Michelle Edwards, Rajkumar Baldeosingh, Manasee Gedam, Gerard A Lutty; Interleukin 33 stimulates Müller cell migration and proliferation.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1481.
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© ARVO (1962-2015); The Authors (2016-present)
We recently described Müller cell membranes occupying the subretinal space in eyes with geographic atrophy (GA). These dense membranes likely create a barrier which will prevent the flow of material, including drugs and/or stem cell treatments, between the retina and subretinal space. This study investigated the Müller cell response to acute and extended exposure to interleukin 33 (IL33), a cytokine released by stressed retinal pigment epithelial (RPE) cells.
The MIO-M1 immortalized human Müller cell line was used to analyze Müller cell proliferation, activation and migration in response to IL33. Migration was assessed using a wound healing assay. MIO-M1 cells were treated with IL33 (1-50ng/ml) at time of injury with or without pretreatment for 24hrs prior to injury. Wound images were collected immediately and at 24hrs. Image J was used to measure the wound area and the percent wound healing was calculated. The effects of IL33 (0.1-100ng/ml) on proliferation were determined by counting cells 48hrs after treatment. A minimum of twelve wells per treatment were analyzed for each assay. Müller cells exposed to IL33 (50ng/ml) for 4 or 24hrs were stained via immunocytochemistry for GFAP, vimentin and glutamine synthetase (GS) to assess activation and morphological changes. Images were collected on a Zeiss 710 confocal microscope. T-tests were used to compare each treatment to controls.
Treatment with IL33 at the time of wound injury did not significantly affect wound healing at 24 hrs. Pretreatment with IL33, however, increased wound healing in a dose dependent manner with all doses (1-50ng/ml) being significant (p<0.05) compared to non-treated cells at 24 hrs. IL33 (0.1-50ng/ml) also significantly (p<0.05) increased MIO-M1 cell proliferation although this response was not dose dependent. The number of cells expressing GFAP increased 4hrs after IL33 treatment but this was not apparent at 24hrs. Similarly, a reduction in GS expression with more diffuse staining was observed at 4hrs but not 24hr after IL33 treatment.
As a regulator of Müller cell proliferation and migration, IL33 could be one factor stimulating Müller cell subretinal membrane formation. The activation of Müller cells by IL33 may stimulate their expression and release of other cytokines. In eyes with GA, IL33 production by RPE cells is likely upregulated, priming Müller cells for membrane formation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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