Classification of Amyloidosis SubTypes by Synchrotron InfraRed MicroSpectroscopy

The aim of this study was to assess the use of Synchrotron Radiation Fourier Transform InfraRed microspectroscopy (SR micro-FTIR) in the diagnosing and subtyping of different misfolded proteins in various tissues and organs. To this end, specimens from various organ sites were analysed by IR biospectroscopy. Multivariate data analysis methods were applied to correlate the spectral datasets with histological and immunohistochemical findings and clinical data. The results of the study reveal significant segregation of tissues affected by amyloidosis and controls, but the amount of amyloid β-sheet did not correlate with the disease state. Amyloid light-chain type specimens contained more β-sheet structures than non-Amyloid A types, and Transthyretrin type showed very little. The Insulin type behaved differently altogether. The amyloid type apparently had a bigger effect on the spectra than the tissue origin. However, there were common spectral changes probably related to tissue damage which indicated the transition from healthy to diseased state. This suggests that not only SR micro-FTIR can be used for detection of amyloidosis, but also for distinguishing different subtypes, and can be an efficient and reliable alternative diagnostic tool in detection and subclassification of amyloid deposits.