Abstract
Purpose :
Silicone oil is used as an endotamponade in combination with vitrectomy. A thinning of the outer nuclear layer under silicone oil tamponade has been found in patients with unexplained loss in visual acuity. An immunological reaction in the fovea due to the exposure of microglial cells to silicone oil has been postulated. We investigate the influence of silicone oil on primary microglia cells.
Methods :
Primary microglia cells were prepared from porcine retina. Microglia identity was assessed with Iba1 staining. Silicone oil was emulsified by sonification. Cell morphology and silicone uptake was evaluated by light microscopy after Coomassie blue staining. Cytokine secretion was evaluated with ELISA. Toxicity of silicone oil on microglia and toxic effect of silicone oil-treated microglia on neuronal cell line PC12 was evaluated with MTT or WST assay.
Results :
Microglia take up silicone oil droplets after 72 hours of incubation. Silicone oil induced no detectable toxicity but increased the metabolism in microglial cells. In addition, the secretion of IL-6 and IL-8, but not of IL-1ß or TNF-α, was induced after 72 hours. Silicone-oil treated microglia did not exert any neurotoxic effect on differentiated PC12 cells but induces an increase in metabolism.
Conclusions :
Emulsified silicone oil changes the activity level of microglia and induces the secretion of IL-6 and IL-8. We could show in our study that microglia react to silicone oil when it emulsifies, given an appropriate exposition time. Our data does not show any toxicity of microglia on neuronal cells within a three-day exposure. Translated to the in-vivo situation this could imply that no acute toxicity is mediated by microglia in silicone treated patients in the early period, but induces an activation of the microglia that may lead to toxic effects in the late period in accordance with clinical data that usually see toxicity after 6 weeks or later.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.