gms | German Medical Science

Background: AMD patients’ sera present an altered systemic complement profile, characterized by elevated levels of complement split products and an increased activity of the alternative complement pathway (Reynolds R et al. 2009, Hecker LA et al. 2010). Among AMD patients CFH and ARMS2 risk genotypes are independently associated with an increased complement activity as well (Smailhodzic D et al. 2012). Based on the presence of active complement components, exposing RPE cells with normal human serum (NHS) leads to an orchestrated increase in intracellular free calcium ([Ca2+]i) (Genewsky A et al. 2014). Thus we investigated the effect of AMD patients’ sera on [Ca2+]i of ARPE-19 cells compared to NHS.

Methods: Using Ca2+ imaging, we analysed the effect of sera from 14 AMD patients with known polymorphisms in the ARMS2 and CFH gene on human ARPE-19 cells.

Results: Exposure to NHS and AMD patients’ sera led to a biphasic increase in [Ca2+]i, consisting of an initial peak and a subsequent phase of sustained [Ca2+]i increase. Compared to NHS AMD patients’ sera caused a significantly modified [Ca2+]i response. Among the AMD patients ARMS2 and/ or CFH risk genotype as well as smoking was correlated with a significantly higher increase in [Ca2+]i. Also prestimulation of ARPE-19 cells with AMD patients’ sera caused a significant higher serum-induced increase in [Ca2+]i, compared to a NHS-prestimulation.

Conclusion: For the first time we investigated the effect of AMD patients’ sera on ARPE-19 cells using Ca2+ imaging. We assume that the modified increase in [Ca2+]i observed in ARPE-19 cells in response to AMD patients’ sera reflects the altered complement profile in AMD patients, especially in smokers and those with ARMS2 and/or CFH risk genotype. A modified Ca2+-response of ARPE-19 after a prestimulation with AMD patients’ sera indicate a long term effect of AMD patients’ sera on ARPE-19 cells.