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Susanne Wasmuth, Katharina Lueck, Albrecht Lommatzsch, Daniel Pauleikhoff; Low Influence Of C5A On Retinal Pigment Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1235.
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Activated complement may be related to the development of age-related macular degeneration (AMD). C5a is an important anaphylatoxin and a side-product during the activation of the complement cascade. This study addressed the influence of C5a on retinal pigment epithelial (RPE) cells that play a key role in AMD.
Human ARPE-19 cells were incubated with recombinant C5a in different fetal calf serum (FCS) concentrations and were stained for C5b-9 using immunocytochemistry. The cell viability was assayed using thiazolyl blue. Reactive oxygen species (ROS) were measured by conversion of nitro blue tetrazolium. The content of vascular epithelial growth factor (VEGF) in the cell culture supernatants was quantified by ELISA. The transepithelial resistance (TER) of ARPE-19 cells cultured on transwell inserts after apical and basal C5a addition was examined.
C5b-9 was not detected in response to C5a treatment. The viability of the RPE cells was only slighly influenced by C5a, even at high doses and prolonged incubation. A slight increase in ROS was found, but the effect was negligible when compared to the influence of FCS. A constitutive VEGF production of the cells was measured. An enhanced secretion of VEGF was mostly dependent on the incubation period. C5a exerted only minor effects. No clear TER alteration through C5a addition was observed.
Our previous findings after complement stimulation resulted in induction of the membrane attacking complex C5b-9 and indicated various AMD-like changes in RPE cells. In contrast, C5a alone had no significant influence on ARPE-19 cells. Although C5a has strong pro-inflammatory effects on other cell types, RPE cells might be more resistant and may need complete assembly of C5b-9.
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