Daniel Havas, Kristina Locker-Kovacovicova, Smriti Mongia
Objective: Histological detection of amyloids in human and mouse brain tissue is complex. Fibril structures and aggregation lead to a reduction of relevant epitopes for primary antibody detection and some amyloids remain undetected in histology samples because of the lack of antibody binding. Binding sites may become internalized within fibrillary aggregates, others become truncated, modified (e.g. phosphorylation, acetylation), and standard histological tissue processing affect binding sites, especially fixation procedures. pFTAA was published to stain diverse amyloids and prions. While commercially available, pFTAA is sparsely used in clinical or preclinical detection. It has many advantages compared to Thioflavin S or Congo including no binding on natural beta-sheet structures, higher sensitivity and specificity, stronger signal, high stability and no toxicity (in vivo tracker).
Methods: Histological sections from standard blocks (FFPE and cryo) in human diseased patients and mouse models to AD, PD, Tauopathy and ALS (SODG93A, rNLS8, APP/PS1, rTg4510, hPFF and mPFF, Line61) were stained with pFTAA and pathological co-markers and imaged on a Zeiss slide scanner.
Results: pFTAA reliably and specifically detected Abeta plaques, neurofibrillary tangles, pTDP-43 and SOD1 aggregates, and human and mouse fibrillary alpha-synuclein inclusions in animal model and human tissue. The amount of specific amyloids varied across the models with some models showing little to no formation of significant amounts of mature amyloids, such as the Line61 or rNLS8 mice.
Conclusions: pFTAA could be the easiest to use and most universal detector for the majority kind of fibrillary amyloid aggregates. Staining is clear and distinct in samples prepared using standard methods. Here we show the detection both of single and mixed human pathology and compare this to prominent preclinical models of amyloid diseases.
Abbreviations
pFTAA = Pentameric formyl thiophene acetic acid
FFPE = formalin fixed Paraffin embedded
AD = Alzheimer’s Disease
PD = Parkinson’s Disease
ALS = amyotrophic lateral sclerosis
hPFF and mPFF = human and mouse preformed fibrils
SOD1 = superoxide dismutase 1
pTDP-43 = phosphorylated Tar DNA binding protein 43