Abstract
Purpose::
In recent studies complex antibody profiles against retinal and optic nerve antigens could be shown in glaucoma patients. The aim of this study was to analyze if sera of patients with glaucoma show effects on survival and protein expression of retinal ganglion cells (R28).
Methods::
Cells from the cell line R 28 were preincubated. Then cells were exposed to DMEM with 10% serum from patients with glaucoma, healthy subjects or serum after antibody removal. These were incubated with or without an elevated pressure of 15000 Pa for 48 hours. After lysis protein profiles were measured by SELDI-TOF using protein chips with two different surfaces (hydrophobic and cationic exchanger arrays). The Seldi-TOF profiles were evaluated by multivariate statistics in order to find the most significant biomarkers. Cell viability was assessed using WST test.
Results::
Sera of glaucoma patients revealed a decrease in cell viability compared to cells incubated with sera of healthy subjects. Differences in protein profiles between the groups of cells depending on treatment could be demonstrated. The different groups consisted of cells incubated with serum from healthy subjects or patients with glaucoma. Both were exposed to elevated as well as atmospheric pressure for 48h. Around 400 different protein and peptide cluster could be detected by Seldi-TOF. A 6 protein biomarker panel was calculated by analysis of discriminance, which detected highly significant differences between treatment groups (Wilks’ Lambda=0.0289, P<0.001). The Mahalanobis distances were calculated and revealed the highest distance from controls in cells incubated with glaucoma sera at elevated pressure (distance=40; P<0.0001). ANOVA was calculated to assess effects of pressure and type of sera on protein profiles, it demonstrated a significant effect in combining glaucoma serum and elevated pressure. The removal of antibodies had a significant effect on protein profiles of cells changing them towards those incubated with healthy serum.
Conclusions::
Glaucoma sera demonstrated a significantly different effect on protein expression in retinal ganglion cells compared to sera from healthy subjects. This was increased if cells were incubated at an elevated pressure. Removal of antibodies showed a change of protein expression in cells which, considering the existence of anti-retinal antibodies in glaucoma sera, could be a further indicator that these antibodies play a role in the appearance of the disease.
Keywords: ganglion cells • retinal culture • proteomics