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Sensitive and rapid assessment of amyloid by oligothiophene fluorescence in subcutaneous fat tissue
Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
Department of Rheumatology & Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Department of Rheumatology & Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-5582-140X
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2015 (English)In: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, E-ISSN 1744-2818, Vol. 22, no 1, 19-25 p.Article in journal (Refereed) Published
Abstract [en]

Systemic amyloidosis (SA) is often diagnosed late. Combining clinical and biochemical biomarkers is necessary for raising suspicion of disease. Fine needle aspiration (FNA) of subcutaneous fat enables SA detection by Congo red staining. The luminescent conjugated probe heptameric formic thiophene acetic acid (h-FTAA) is a sensitive alternative to Congo red-staining of tissue samples. Our objective was to compare h-FTAA fluorescence with the Congo red stain for amyloid detection in FNA-obtained fat tissue. Herein, we studied samples from 57 patients with established SA (19 with AA, 20 with AL, and 18 with ATTR) and 17 age-matched controls (34–75 years). Positivity for h-FTAA was graded according to a Congo red-based grading scale ranging from 0 to 4+. Amyloid grading by both methods correlated strongly (r = 0.87). Here h-FTAA was positive in 53 of 54 Congo red-positive cases (sensitivity 98%) and h-FTAA was negative in 7 of 17 Congo red-negative controls (specificity 41%), but was also positive for 3 Congo red-negative SA cases. We conclude that h-FTAA fluorescence is more sensitive than Congo red staining in this small exploratory study of fat tissue samples, implicating potential sensitivity for prodromal amyloidosis, but is less specific for clinical amyloidosis defined by Congo red positivity. Given its simplicity h-FTAA staining may therefore be the most appropriate method for rapid screening of fat tissue samples but should presently treat grade 1+ as only suggestive, whereas 2+ or higher as positive for amyloidosis. Parallel assessment of h-FTAA and Congo red staining appears highly promising for clinical applications.

Place, publisher, year, edition, pages
Informa Healthcare, 2015. Vol. 22, no 1, 19-25 p.
Keyword [en]
AA amyloidosis, amyloid light chain, hyper spectral imaging, systemic amyloidosis, transthyretin
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:liu:diva-117806DOI: 10.3109/13506129.2014.984063ISI: 000352637800003PubMedID: 25847117OAI: oai:DiVA.org:liu-117806DiVA: diva2:811262
Note

At the time for thesis presentation publication was in status: Manuscript

Funding Agencies|European Commission; Swedish Foundation for Strategic Research; Swedish Research Council; Linkoping University Center for Neuroscience; European Research Council

Available from: 2015-05-11 Created: 2015-05-08 Last updated: 2017-01-11Bibliographically approved
In thesis
1. Luminescent molecular recognition of pathognomonic and aging associated protein aggregates
Open this publication in new window or tab >>Luminescent molecular recognition of pathognomonic and aging associated protein aggregates
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Various protein inclusions have been recognized to be associated with aging and pathogenic conditions, such as in Alzheimer’s disease, Parkinson’s disease, Type 2 diabetes, and the prionoses Creutzfeldt-Jakob disease, Chronic wasting disease (CWD), and Mad cow disease. The causative transition of protein aggregation is the alteration in the conformation of the protein that renders the protein susceptible towards self-assembly. Variations in the physico-chemical ultrastructure of the protein deposit, i.e. the conformation and the chemical nature of the fibril constituent protein monomers, translate into specific structure-property phenotype, hence clinicopathology. Upon transmission and/or propagation this phenomenon gives rise to specific protein aggregate strains. Today most potential treatments of the protein conformational diseases have been a huge failure, effectively due to late diagnosis and subsequent therapeutic intervention. An imperative for efficient treatment is early detection and accurate identification for proper clinical diagnosis.

The purpose of the studies in this thesis was to develop highly sensitive methods for detection and discrimination of age- and disease associated protein deposits both for in vitro and ex vivo utilization.

Herein we have shown that, for in vitro usage, Nile red will bind to amyloid-like protein aggregates derived from a plethora of precursor proteins. It was also found that the fluorescence was insensitive to acidic assay conditions in contrast to the standard in vitro dye Thioflavin T (ThT). Further, Nile red was shown to discriminate between conformational isoforms thus enabling conformational typing of amyloid structures.

For the development of ex vivo detection methods we employed luminescent conjugated oligothiophenes (LCOs) and utilized the structure-conformation induced optical properties of this class of protein aggregate ligands. The heptameric oligothiophene h-FTAA was successfully used to detect, with high sensitivity, protein deposits from various systemic amyloidoses (ATTR, AA, AL-λ/κ, and the local amyloidosis AIAPP) derived from biopsy specimens. Also aging-associated protein deposits were detected which was found promising for early detection of potentially pathogenic protein inclusions. Further, LCO staining of tissue sections was found compatible with immunolabeling enabling subtyping of involved proteins. Early detection of amyloidosis also requires relatively non-invasive methods, why h-FTAA staining was directed towards fine-needle-aspirated (FNA) abdominal fat tissue smears. Staining of protein deposits and detection with high sensitivity was also found in the fat tissue smears.

In addition to the relatively rare prionoses it has lately been shown that Alzheimer’s, Parkinson’s diseases share similar properties as the prion pathologies. Hence the urgent need for ligands that will recognize specific disease specific strain aggregates. Using an established murine model for prion strain propagation we were able to discriminate two different prion strains, murine adapted Sheep Scrapie (mSS) and murine adapted Chronic wasting disease (mCWD) from each other by using multimodal fluorescence microscopy entailing emission/excitation spectral imaging and fluorescent lifetime imaging (FLIM).

In conclusion we have shown that the LCOs will recognize protein aggregates with high sensitivity and selectivity. In addition we have shown that the LCOs detect protein aggregates that Congo red failed to recognize thus allowing potentially early diagnosis. Last, we show that the LCOs will recognize and discriminate between different protein aggregate strains which potentially will allow disease specific therapeutic targeting.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. 77 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1596
National Category
Chemical Sciences Natural Sciences
Identifiers
urn:nbn:se:liu:diva-106878 (URN)978-91-7519-334-2 (ISBN)
Public defence
2014-06-11, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 14:15 (Swedish)
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Available from: 2014-05-23 Created: 2014-05-23 Last updated: 2017-01-11Bibliographically approved

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