Abstract
Purpose:
Reduced choroidal blood flow may create hypoxia in the retina, triggering formation of new vessels through the activation of vascular endothelial growth factor. This may initiate neovascular age-related macular degeneration.Glycated human serum albumin (GHSA) has been shown to stimulate RPE cells to produce IL-8 and MCP-1. Early glycated albumin may have a direct impact on cell function during ageing. Minocycline is a semisynthetic derivative of tetracycline with a longer half life and improved penetration through the blood brain barrier. Apart from antimicrobial effects it also has potent anti-inflammatory and immunomodulatory effects. It<br /> was postulated that minocyline may suppress the induced expresion of inflammatory cytokines from retinal pigment epithelial cells in culture.
Methods:
Research was conducted on human ARPE-19 cells in culture. Cells were exposed to hypoxia and GHSA. Minocycline was investigated for the effect on cell growth and cell viability. Cell counts were obtained with a Scepter cell counter (Millipore). Cell viability and apoptosis rates were investigated with annexin V and propidium iodide staining by flow cytometry. The effects of hypoxia and different concentrations of GHSA, IL-1â, TNF-á on cell viability and with treatment with minocycline were investigated. ELISA for IL-8 and MCP-1 was conducted with appropriate negative and positive controls. Standards and samples were analysed in duplicate. Intraplate and interplate reproducibility tests were performed.
Results:
Cell viability decreased at minocycline doses above 5mM. Hypoxia increased the proportion of non viable cells and cells undergoing apoptosis and minocycline treated cells had a lower proportion in the early stage of apoptosis. ELISA results demonstrated that hypoxia and GHSA treated cells showed a significantly increased MCP-1 production. Minocycline significantly reduced MCP-1 production in normoxic conditions (p< 0.01)and also decreased MCP-1 production in hypoxia (p<0.05). For IL-8, minocycline significantly reduced production in normoxia (p<0.01) but not statistically significantly under hypoxia.
Conclusions:
The results suggest that minocycline abrogates the production of inflammatory cytokines IL-8 and MCP-1 in cell culture and minocycline may have a therapeutic role in the treatment of inflammatory changes in age related macular degeneration.