Abstract
Purpose :
We have demonstrated complement C3 has a critical role in the formation of sub-RPE basal laminar deposits in a mouse model of EFEMP1-associated macular degeneration and in the formation of basal deposits by primary cultures of RPE cells from these mutant mice. Several lines of evidence suggest a role of complement C5 in deposit formation. The goal of this project was to determine if complement C5 is involved in the formation of basal deposits induced by the R345W mutation in Efemp1.
Methods :
Homozygous double mutant (Efemp1R345W/C5null), C5 null, Efemp1R345W and wild type mice were generated from crossing C5 null and Efemp1R345W mice. At 14 months eye cups from each mouse line were prepared and were fixed for transmission electron microscopy (TEM). The amount of basal deposits was scored using ImageJ. Primary RPE cells from each mouse line were cultured in transwells for 2 weeks when the cells formed a pigmented hexagonal monolayer. The presence and amount of sub-RPE basal deposit were assessed by electron microscopy.
Results :
In the absence of complement C5, the number and size of basal laminar deposits in Efemp1R345W mice were diminished but not eliminated. The cultures of Efemp1R345W RPE cells also formed fewer sub-RPE deposits in the absence of complement C5. The conditioned media from cultures of the Efemp1R345W/C5 null mice, however, showed significantly higher levels of complement C3 than media from cultures of wild type or Efemp1R345W RPE cells.
Conclusions :
The results suggest that complement C5 contributes to the formation of basal deposits in Efemp1R345W mice and by RPE cells from the mutant mice. The results are consistent with basal deposit formation being dependent on both complement C3a and on complement C5.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.