Abstract
Purpose:
Early stages of Age related Macular Degeneration (AMD) are characterized by dysfunction and degeneration of the retinal pigment epithelium (RPE) cells. These alterations participate in the death of the overlying photoreceptors ultimately leading to loss of vision. It is therefore crucial to understand this initial event in order to prevent the pathology development. Gangliosides (GG) make a wide family of sialic acid-containing glycosphingolipids. Both the oligosaccharidic chain and the ceramide moiety (sphingoïd base and fatty acid) exhibit a huge heterogeneity in their structure. The biological role of this heterogeneity is largely unknown. GG are particularly abundant in the central nervous system, including the retina. While their developmental and neuroprotective actions have been demonstrated, their precise role in retina’s function and its pathologies is still poorly understood. In the present study, we aimed to investigate the role of GG in the response of RPE cells to inflammation, which is known as one of the pathophysiological features of AMD.
Methods:
Cultured human RPE cells (ARPE19) were exposed to an inflammatory cytokine mix (ICM): TNF-α, IL-1β and IFN-γ for 72 hours. Cell viability was assessed by direct cell counting and measurement of total DNA content. GG were analyzed by Reversed Phase High Pressure Liquid Chromatography, coupled with tandem mass spectrometry (RPHPLC-ESI-MSMS).
Results:
ICM had deleterious effects on ARPE19 viability. Indeed, the cell number decreased by half between control and treated conditions based both on cell counting and measurement of DNA content. GM3 appeared to be the main GG class present in ARPE19 cells. Interestingly, ICM exposure was associated with modifications in the GM3 profile. Especially, the relative amounts of d16:1/18:0 and/or d18:1/16:0 species increased whereas those of the d18:1/24:1 and the d18:1/24:0 and/or d20:1/22:0 species decreased. These changes reflected an increase in short chain fatty acids to the detriment of long chain fatty acids.
Conclusions:
Our observations suggest that GG might be implicated in ARPE19 cell response to inflammatory cytokines. Further investigations are required to understand the precise biological role of this change in fatty acid profile of GM3 in the deleterious effects of inflammation on RPE cells.
Keywords: 701 retinal pigment epithelium •
490 cytokines/chemokines •
541 glycoconjugates/glycoproteins