A team of scientists at Sweden’s Linkoping University have developed a molecular probe that can detect an array of different amyloid deposits in several human tissues. This new probe is extremely sensitive and was used at very low concentrations to correctly identify every positive amyloidosis sample when compared to the traditional clinical tests. The probe also picked up some amyloidosis signals that the traditional methods were unable to detect. This result means that the new probe could be used to detect amyloidosis before symptoms present, leading to faster and hence more effective treatment.
Amyloidosis is a general term for several different types of disease. Aggregates of amyloid proteins form and deposit in different tissues which can affect the normal function. As the disease progresses and amyloid deposits grow, tissues become irreversibly damaged. Amyloid deposits can be found in many different organs leading to a wide range of possible symptoms and making diagnosis challenging.
To date, the primary mode of diagnosis for amyloidosis has been the Congo red stain. However, evidence from the Linköping team, presented in Amyloid Journal show that their new probe is much more sensitive, being able to detect small amyloid deposits in samples that were previously determined to be amyloid-free.
“Given the sensitivity of the probe, we think this would make an excellent complement to traditional methods and could eventually be a replacement”, says lead investigator Per Hammarström, professor at Linköping University.
According to the U.S. Office of Rare Diseases (ORD), a subsidiary of the National Institute of Health (NIH), amyloidosis is a rare disease, affecting less than 200,000 people in the U.S.. However, The Amyloidosis Foundation suspects that the figures are underreported and that amyloidosis is not that rare – just rarely diagnosed. A more sensitive diagnostic method would help to uncover the reality of the situation.
The Linköping team are optimistic about the use of the probe.
“It could also be used to identify new types of amyloids and presymptomatic patients who are at risk of developing the disease”, says Hammarström and collaborator professor Peter Nilsson.
Research is continuing in this important field. In the future, the researchers hope to apply this to other diseases where amyloids are present and develop real-time, non-invasive diagnostic probes.
Funding: This study was made possible by support from: Swedish Foundation for Strategic Research (KPRN), The Swedish Research Council (PH, GTW), The Göran Gustafsson Foundation (PH) Linköping University Center of Neuroscience (DS) the European Research Council (ERC starting grant; Project MUMID) (KPRN), the EU-FP7 Health programme project LUPAS (KPRN, PH) and the patients’ associations FAMY, FAMY Norrbotten and Amyl (PW).
Source: Åke Hjelm – Linköping University
Image Source: The image is adapted from the Linköping University press release.
Original Research: Full open access research for “Establishing the fluorescent amyloid ligand h-FTAA for studying human tissues with systemic and localized amyloid” by Daniel Sjölander, Christoph Röcken, Per Westermark, Gunilla T. Westermark, K Peter R Nilsson and Per Hammarström in Amyloid. Published online March 17 2016 doi:10.3109/13506129.2016.1158159
Establishing the fluorescent amyloid ligand h-FTAA for studying human tissues with systemic and localized amyloid
Rapid and accurate detection of amyloid deposits in routine surgical pathology settings are of great importance. The use of fluorescence microscopy in combination with appropriate amyloid specific dyes is very promising in this regard. Here we report that a luminescent conjugated oligothiophene, h-FTAA, rapidly and with high sensitivity and selectivity detects amyloid deposits in verified clinical samples from systemic amyloidosis patients with AA, AL and ATTR types; as well as in tissues laden with localized amyloidosis of AANF, AIAPP and ASem1 type. The probe h-FTAA emitted yellow red fluorescence on binding to amyloid deposits, whereas no apparent staining was observed in surrounding tissue. The only functional structure stained with h-FTAA showing the amyloidotypic fluorescence spectrum was Paneth cell granules in intestine. Screening of 114 amyloid containing tissues derived from 107 verified (Congo red birefringence and/or immunohistochemistry) amyloidosis patients revealed complete correlation between h-FTAA and Congo red fluorescence (107/107, 100% sensitivity). The majority of Congo red negative control cases (27 of 32, 85% specificity) were negative with h-FTAA. Small Congo red negative aggregates in kidney, liver, pancreas and duodenum were found by h-FTAA fluorescence in five control patients aged 72–83 years suffering from diverse diseases. The clinical significance of these false-positive lesions is currently not known. Because h-FTAA fluorescence is one magnitude brighter than Congo red and as the staining is performed four magnitudes lower than the concentration of dye, we believe that these inclusions are beyond detection by Congo red. We conclude that h-FTAA is a fluorescent hypersensitive, rapid and powerful tool for identifying amyloid deposits in tissue sections. Use of h-FTAA can be exploited as a rapid complementary technique for accurate detection of amyloid in routine surgical pathology settings. Our results also implicate the potential of the technique for detection of prodromal amyloidosis as well as for discovery of new amyloid-like protein aggregates in humans.
“Establishing the fluorescent amyloid ligand h-FTAA for studying human tissues with systemic and localized amyloid” by Daniel Sjölander, Christoph Röcken, Per Westermark, Gunilla T. Westermark, K Peter R Nilsson and Per Hammarström in Amyloid. Published online March 17 2016 doi:10.3109/13506129.2016.1158159
