MALDI mass spectrometry imaging unravels organ- and amyloid-type specific peptide signatures in pulmonary and gastrointestinal amyloidosis.

Purpose Amyloidosis is a disease group caused by pathological aggregation and deposition of peptides in diverse tissue sites. Recently, matrix-assisted laser desorption/ionization mass spectrometry imaging coupled with ion mobility separation (MALDI-IMS MSI) was introduced as a novel tool to identify and classify amyloidosis using single sections from formalin-fixed and paraffin-embedded cardiac biopsies. Here, we tested the hypothesis that MALDI-IMS MSI can be applied to lung and gastrointestinal specimens. Experimental design 46 lung and 65 gastrointestinal biopsy- and resection specimens with different types of amyloid were subjected to MALDI-IMS MSI. 93 specimens included tissue areas without amyloid as internal negative controls. Nine cases without amyloid served as additional negative controls. Results Utilizing a peptide filter method and 21 known amyloid specific tryptic peptides we confirmed the applicability of a universal peptide signature with a sensitivity of 100% and a specificity of 100% for the detection of amyloid deposits in the lung and gastrointestinal tract. Additionally, the frequencies of individual m/z-values of the 21 tryptic marker peptides showed organ- and tissue type specific differences. Conclusions and clinical relevance MALDI-IMS MSI adds a valuable analytical approach to diagnose and classify amyloid and the detection frequency of individual tryptic peptides is organ-/tissue type specific. This article is protected by copyright. All rights reserved.