The Nomenclature Committee of the International Society of Amyloidosis (ISA) met during the XVth Symposium of the Society, 3 July–7 July 2016, Uppsala, Sweden, to assess and formulate recommendatio...

https://www.tandfonline.com/doi/pdf/10.1080/13506129.2016.1257986

Amyloid fibril proteins and amyloidosis: chemical identification and clinical classification International Society of Amyloidosis 2016 Nomenclature Guidelines.

Systemic amyloidosis is a rare protein misfolding and deposition disorder leading to progressive organ failure. There are over 15 types of systemic amyloidosis, each caused by a different precursor protein which promotes amyloid formation and tissue deposition. Amyloidosis can be acquired or hereditary and can affect various organs, including the heart, kidneys, liver, nerves, gastrointestinal tract, lungs, muscles, skin and soft tissues. Symptoms are usually insidious and nonspecific resulting in diagnostic delay. The field of amyloidosis has seen significant improvements over the past decade in diagnostic accuracy, prognosis prediction and management. The advent of mass spectrometry-based shotgun proteomics has revolutionized amyloid typing and has led to the discovery of new amyloid types. Accurate typing of the precursor protein is of paramount importance as the type dictates a specific management approach. In this article, we review each type of systemic amyloidosis to provide the practitioner with practical tools to improve diagnosis and management of these rare disorders.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/joim.13169

Systemic amyloidosis from A (AA) to T (ATTR): a review.

OBJECTIVE To map the occurrence of amyloid types in a large clinical cohort using mass spectrometry-based shotgun proteomics, an unbiased method that unambiguously identifies all amyloid types in a single assay. METHODS A mass spectrometry-based shotgun proteomics assay was implemented in a central reference laboratory. We documented our experience of typing 16,175 amyloidosis specimens over an 11-year period from January 1, 2008, to December 31, 2018. RESULTS We identified 21 established amyloid types, including AL (n=9542; 59.0%), ATTR (n=4600; 28.4%), ALECT2 (n=511; 3.2%), AA (n=463; 2.9%), AH (n=367; 2.3%), AIns (n=182; 1.2%), KRT5-14 (n=94; <1%), AFib (n=71; <1%), AApoAIV (n=57; <1%), AApoA1 (n=56; <1%), AANF (n=47; <1%), Aβ2M (n=38; <1%), ASem1 (n=34; <1%), AGel (n=29; <1%), TGFB1 (n=29; <1%), ALys (n=15; <1%), AIAPP (n=13; <1%), AApoCII (n=11; <1%), APro (n=8; <1%), AEnf (n=6; <1%), and ACal (n=2; <1%). We developed the first comprehensive organ-by-type map showing the relative frequency of 21 amyloid types in 31 different organs, and the first type-by-organ map showing organ tropism of 18 rare types. Using a modified bioinformatics pipeline, we detected amino acid substitutions in cases of hereditary amyloidosis with 100% specificity. CONCLUSION Amyloid typing by proteomics, which effectively recognizes all amyloid types in a single assay, optimally supports the diagnosis and treatment of amyloidosis patients in routine clinical practice.

Amyloid Typing by Mass Spectrometry in Clinical Practice: a Comprehensive Review of 16,175 Samples.

Amyloidoses are a spectrum of disorders caused by abnormal folding and extracellular deposition of proteins. The deposits lead to tissue damage and organ dysfunction, particularly in the heart, kidneys, and nerves. There are at least 30 different proteins that can cause amyloidosis. The clinical management depends entirely on the type of protein deposited, and thus on the underlying pathogenesis, and often requires high-risk therapeutic intervention. Application of mass spectrometry-based proteomic technologies for analysis of amyloid plaques has transformed the way amyloidosis is diagnosed and classified. Proteomic assays have been extensively used for clinical management of patients with amyloidosis, providing unprecedented diagnostic and biological information. They have shed light on the pathogenesis of different amyloid types and have led to identification of numerous new amyloid types, including ALECT2 amyloidosis, which is now recognized as one of the most common causes of systemic amyloidosis in North America.

Amyloidosis: Insights from Proteomics.

Apolipoprotein C-III has been referred to as an important participant in the metabolism of triglyceride-rich lipoproteins, leading to hypertriglyceridemia and thereafter cardiovascular disease. Accumulating evidence indicates that apolipoprotein C-III is a multifaceted protein which not only regulates triglyceride metabolism, but also participates in the atherosclerotic lesion formation and several other pathological processes involved in atherosclerosis. Based on data from experiments and clinical trials, some novel therapies such as antisense technology emerge.

/pdf/the-emerging-role-of-apolipoprotein-c-iii-beyond-effects-on-34jge5c48q.pdf

The emerging role of apolipoprotein C-III: beyond effects on triglyceride metabolism.

Apolipoprotein C-III deficiency provides cardiovascular protection, but apolipoprotein C-III is not known to be associated with human amyloidosis. Here we report a form of amyloidosis characterized by renal insufficiency caused by a new apolipoprotein C-III variant, D25V. Despite their uremic state, the D25V-carriers exhibit low triglyceride (TG) and apolipoprotein C-III levels, and low very-low-density lipoprotein (VLDL)/high high-density lipoprotein (HDL) profile. Amyloid fibrils comprise the D25V-variant only, showing that wild-type apolipoprotein C-III does not contribute to amyloid deposition in vivo. The mutation profoundly impacts helical structure stability of D25V-variant, which is remarkably fibrillogenic under physiological conditions in vitro producing typical amyloid fibrils in its lipid-free form. D25V apolipoprotein C-III is a new human amyloidogenic protein and the first conferring cardioprotection even in the unfavourable context of renal failure, extending the evidence for an important cardiovascular protective role of apolipoprotein C-III deficiency. Thus, fibrate therapy, which reduces hepatic APOC3 transcription, may delay amyloid deposition in affected patients.

/pdf/d25v-apolipoprotein-c-iii-variant-causes-dominant-hereditary-31oyu47d3w.pdf

Athina D. Kalopissis

Papers

D25V apolipoprotein C-III variant causes dominant hereditary systemic amyloidosis and confers cardiovascular protective lipoprotein profile