Session: Session 2

Mass spectrometry-based proteomics in amyloid typing

Etienne BANCAL¹, Jessica DALLOUX-CHIOCCIOLI², Rodica ANESIA², Clement ROBIN¹, Lucie COMBES¹, Mylène CAMUS¹, Emmanuelle MOUTON-BARBOSA¹, Magali COLOMBAT², Odile SCHILTZ¹

¹Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France, Toulouse, France
²Département d’Anatomie Pathologique, Institut Universitaire du Cancer IUCT-O, CHU Toulouse, Toulouse, France (Department of Pathology, University Hospital of Toulouse, University Cancer Institute of Toulouse, Toulouse, France), Toulouse, France

Amyloidosis is a group of rare and potentially fatal diseases characterized by the deposition of misfolded extracellular proteins forming insoluble, highly ordered amyloid fibrils. These deposits may occur in a single tissue (localized amyloidosis) or in several tissues (systemic amyloidosis). Amyloid fibrils progressively disrupt tissue structure and exert a toxic effect on adjacent cells, leading to organ dysfunction. To date, 42 different proteins are known to form amyloid fibrils in humans. To ensure an effective patient management, it is crucial to identify the protein responsible for amyloid deposits. Treatments are now available for the main types of amyloidosis, derived from the lambda and kappa immunoglobulin (AL) light chains, as well as from transthyretin (ATTR). Traditionally, amyloid typing has been performed by immunostaining on frozen and fixed tissue sections. However, commercial antibodies are often of insufficient quality to recognize proteins in amyloid tissue, making immunostaining limited.

The CHU in Toulouse therefore sought to collaborate with a laboratory specializing in proteomic analysis based on mass spectrometry (MS) combined with laser microdissection. This combination provides a better diagnosis of rare amyloidosis. Our pipeline is based on a Bottom-Up method using UniProt databases to identify amyloidosis proteins in patients with clinical signs.

This method enables us to type 95% of amyloidosis, whereas immunostaining enables us to type about 50% of amyloidosis cases.