Abstract
Purpose :
Pre-symptomatic detection of neurodegeneration and subsequent early intervention is vital to the successful treatment of neurodegeneration. As retinal amyloid beta deposits (Aβ) are reported to predate the onset of Alzheimer’s Disease (AD) symptoms by over a decade, the non-invasive labelling of these species could provide a critical advancement in developing disease-modifying treatment. Building upon previous work in which a confocal laser scanning ophthalmoscope (cSLO) captured the in vivo fluorescence signal from intranasally administered curcumin to differentiate triple transgenic AD model mice (3xTg) from healthy c57 mice, the present study aimed to confirm the hypothesis that retinal curcumin fluorescence reflects Aβ labelling using the 6e10 antibody.
Methods :
10 Female 3xTg mice (Jackson labs) and 10 C57 control animals (Jackson labs), up to 10 months of age received 10 µL of an intranasal curcumin formulation, 2 hours prior to cSLO imaging and perfusion with 4% paraformaldehyde. The Aβ antibody 6E10 (with a 647 nm fluorescent secondary antibody) was incubated to immunostain flat-mount retinas. Fluorescent microscopy with an automated stage was used to image whole retinas as a tile scan. Images were subsequently overlaid to identify colocalisation.
Results :
Frequent colocalisation of 6E10 and curcumin fluorescence was observed ex vivo, with curcumin administered in vivo appearing to label both intracellular and extracellular Aβ deposits. Particle count analysis indicated significantly more Aβ labelling (as measured by both curcumin and 6E10) in 3xTg tissue than C57 (p<.05), corroborating in vivo cSLO data.
Conclusions :
Intranasally administered curcumin appears to label retinal Aβ, as corroborated by colocalisation with the 6E10 antibody. This replicates previous experiments demonstrating the specific binding activity of curcumin to Aβ, including in human tissue. The present results provide a strong foundation for the further development of this technology.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.