Abstract
Purpose :
Age-related macular degeneration (AMD) is a complex disease influenced by both environmental and genetic risk factors. Previous studies have showed a significant association between the components of the complement system and dry AMD. Complement factor D (CFD), a type of serine protease, splits factor B in the C3bB complex into C3bBb in the alternative pathway, thereby aiding the amplification loop and the activation of the alternative pathway. This study delved into the expression of CFD mRNA and protein in both normal and AMD human eyes.
Methods :
Paraffin sections from both normal (n=2) and AMD (n=2) eyes were utilized to identify CFD mRNA expression through RNAscope. To determine CFD protein expression, paraffin sections from normal (n=6) and AMD eyes (n=12), sourced from donors aged between 39 and 93 years, were subjected to immunostaining. The primary antibody was initially tested on human paraffin sections of the brain, adipose tissue, breast, and heart. The secondary antibody was employed solely as a negative control.
Results :
CFD mRNA expression was weakly observed in both normal and AMD eyes, specifically in the neural retina and choroid cells, but not in the retinal pigment epithelium cells (RPEs). CFD protein was identified in the RPE, choriocapillaris, and choroid of both normal and AMD eyes. In this limited study, no significant difference in CFD protein expression was observed between the normal and AMD eyes.
Conclusions :
Our findings present evidence of CFD mRNA and protein expression in both normal and AMD-affected human eyes. We hypothesize that the CFD protein in the RPE originates from systemic circulation. To test this, further studies involving a larger sample of human donor eyes are required.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.