Esterified and unesterified cholesterol in drusen and basal deposits of eyes with age-related maculopathy.
To address the potential for an outer segment (OS) contribution to the sub-retinal pigment epithelium (RPE) lesions of age-related maculopathy (ARM), we quantified esterified and unesterified cholesterol (EC, UC) with the sterol-specific fluorescent probe filipin in cryosections of ARM eyes. Twenty six eyes from 20 donors were preserved <5 hr after death in 4% paraformaldehyde (n = 16) or 2.5% glutaraldehyde/1% paraformaldehyde (n = 10). Eyes had exudative late ARM (n = 6), geographic atrophy (n = 15), and drusen > or =125 microm (n = 11). Sections were stained with filipin for UC or were extracted and hydrolysed with cholesterol esterase before filipin staining for EC. Drusen varied in cholesterol content, with a rough correlation between EC and UC. Dome-shaped drusen contained distinctive, loosely packed UC-rich loops. In basal deposits, EC and UC were more prominent near Bruch's membrane than near the RPE. A UC-rich material was localized within the subretinal space (n = 4). Maximum filipin fluorescence due to UC was quantified in 47 lesions (19 drusen, 24 basal deposits, and 4 sub-retinal) from 12 ARM eyes and compared to OS and inner plexiform layer (IPL) of uninvolved retina in the same sections. Relative to IPL, UC fluorescence was higher in lesions (mean+/-s.d: 1.63+/-0.69) and lower in OS (0.64+/-0.18). If only the packing of membranes explained fluorescence intensity, then one would expect much higher intensities in membrane-rich OS than in lesions. Because the converse is true, the membranous material in lesions must be more highly enriched in cholesterol on a per unit area basis. UC in sub-RPE deposits cannot be derived directly from OS without considerable intracellular processing within RPE, additional cholesterol sources, or both.
Curcio
Christine A
CA
Department of Ophthalmology, Callahan Eye Foundation Hospital, University of Alabama School of Medicine, 700 South 18th Street, Room H020, Birmingham AL 35294-0009, USA. curcio@uab.edu
Presley
J Brett
JB
Malek
Goldis
G
Medeiros
Nancy E
NE
Avery
Dina V
DV
Kruth
Howard S
HS
D000368:Aged; D000369:Aged, 80 and over; D016570:Bruch Membrane / Q000737:chemistry; D002784:Cholesterol / Q000032:analysis*; D015925:Cryopreservation; D004951:Esterification; D005260:Female; D005372:Filipin; D006801:Humans; D008268:Macular Degeneration / Q000378:metabolism*; D008297:Male; D008856:Microscopy, Fluorescence; D010857:Pigment Epithelium of Eye / Q000737:chemistry; D015593:Retinal Drusen / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000737:chemistry
D005372:Filipin; D002784:Cholesterol