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A reliable diagnosis of amyloidosis is usually based on a tissue biopsy. With increasing options for specific treatments of the different amyloid diseases, an exact and valid diagnosis including determination of the biochemical fibril nature is imperative. Biopsy sites as well as amyloid typing principles vary and this paper describes methods employed at some laboratories specialised in amyloidosis in Europe, Japan and USA.

Background: The aim of the present prospective study (ClinicalTrials.gov Identifier: NCT02111538) was to assess the prognostic value of phase angle (PhA), derived from bioimpedance vectorial analysis (BIVA), in patients affected by systemic amyloid light-chain (AL) amyloidosis. Methods: One hundred-twenty seven consecutive newly diagnosed, treatment-naïve patients with histologically confirmed AL amyloidosis were enrolled. Nutritional assessment including BIVA-derived PhA was performed before treatment initiation. Results: PhA was associated with unintentional weight loss, caloric intake and the physical component of quality of life (QoL). After a median follow-up of 16.3 months (25th-75th percentile: 8.4-28.9 months), 49 (38.6%) subjects had died. At multivariable Cox proportional hazard analysis, PhA ≤4.3 independently predicted survival (HR = 2.26 [95%CI, 1.04-4.89]; p  = .038]) after controlling for hydration status, haematologic response to treatment and modified Mayo Clinic cardiac stage. There was no effect modification of PhA on mortality by cardiac stage (P for interaction = 0.61). Conclusions: In AL amyloidosis, BIVA-derived PhA is associated with the common parameters implied in malnutrition assessment and QoL, and adjusted for hydration independently predicts survival. Due to its feasibility, BIVA should be systematically considered for the nutritional and clinical assessment of AL patients, in whom nutritional intervention trials are warranted.

Abnormalities in protein folding are involved in many localized and systemic diseases, all of which are characterized by insoluble amyloid formation and deposition. In immunoglobulin light chain (LC) amyloidosis, the most frequent systemic form of amyloidosis, the amyloid involvement of the heart dictates the prognosis and the elucidation of the mechanism of heart targeting and toxicity is essential for designing and testing new effective treatments. To this end, the availability of an appropriate animal model is crucial. We recently described the use of C. elegans as an innovative experimental system to investigate in vivo the pathogenic effects of monoclonal LC. This idea stems from the knowledge that the worm's pharynx is an "ancestral heart" with the additional ability to recognize stressor compounds. The feeding of worms with LC purified from patients suffering from cardiomyopathy, selectively and permanently impaired the pharyngeal function. This irreversible damage resulted in time, in a significant reduction in the lifespan of worms. We also reported that the ability of LC to generate reactive oxygen species was associated with their toxic effects and was counteracted by anti-oxidant compounds. This new nematode-based assay represents a promising model for elucidating the heart-specific toxicity of LC and for a rapid screening of new therapeutic strategies.

Abstract The clinical phenotype of familial ATTR amyloidosis depends to some extent on the particular mutation, but differences exist also within mutations. We have previously described that two types of amyloid fibril compositions exist among Swedish ATTRV30M amyloidosis patients, one consisting of a mixture of intact and fragmented ATTR (type A) and one consisting of mainly intact ATTR (type B). The fibril types are correlated to phenotypic differences. Patients with ATTR fragments have a late onset and develop cardiomyopathy, while patients without fragments have an early onset and less myocardial involvement. The present study aimed to determine whether this correlation between fibril type and phenotype is valid for familial ATTR amyloidosis in general. Cardiac or adipose tissues from 63 patients carrying 29 different TTR non-V30M mutations as well as 13 Japanese ATTRV30M patients were examined. Fibril type was determined by western blotting and compared to the patients' age of onset and degree of cardiomyopathy. All ATTR non-V30M patients had a fibril composition with ATTR fragments, except two ATTRY114C patients. No clear conclusions could be drawn about a phenotype to fibril type correlation among ATTR non-V30M patients. In contrast, Japanese ATTRV30M patients showed a similar correlation as previously described for Swedish ATTRV30M patients. This study shows that a fibril composition with fragmented ATTR is very common in ATTR amyloidosis, and suggests that fibrils composed of only full-length ATTR is an exception found only in a subset of patients.

In Transthyretin amyloidosis (ATTR), tissue deposition of transthyretin fibrils translates into a significant subversion of the tissues proteome. We used multidimensional protein identification technology for profiling the proteome of subcutaneous adipose tissue in patients with ATTR, in comparison with controls and patients with other types of amyloidoses, to identify the global proteomic changes related specifically with this disease. The adipose tissue proteome of five ATTR patients and 11 non-affected controls was analyzed. Samples from patients with Light Chain (AL) or reactive (AA) amyloidosis were studied alongside. In all ATTR samples, mass spectrometry data showed that transthyretin was specifically up-represented, being a marker of the nature of the deposits. Tissue resident proteins, involved in key biological processes, were also found to be differently represented compared to controls. The high-throughput analysis of the proteome of amyloid affected fat, combined with bioinformatic data interpretation, is a powerful tool for identification of perturbed protein expression in ATTR amyloidosis.

Amyloidoses are characterized by the presence of extracellular amyloid deposits, constituted by fibrillar aggregates of misfolded proteins. Despite the similar morphologic appearance of fibrils, at least 28 different proteins have been detected as causative agents of human amyloidoses, 14 of which associated with systemic forms. Unequivocal typing of the amyloid deposits is a key step in the management of these diseases. Existing drawbacks of traditional, immunohistochemistry-based techniques have driven the search for alternative solutions for direct amyloid typing. Proteomics indicates the comprehensive study of the proteins in a biological sample, centered on analysis by mass spectrometry. The great potential of this approach in describing the composition of amyloid deposits and in studying the molecular features of the amyloidogenic precursors has become immediately clear and the introduction of proteomics in the clinical practice has revolutionized the field of amyloid typing. This review provides a critical overview of the various approaches that have been proposed in this specific context, along with a brief description of the proteomic methods for assessment of the circulating amyloidogenic proteins.

Background: Cardiac biomarkers play a major role in the identification of patients at risk of early death in AL amyloidosis, and a staging system based on amino-terminal pro-natriuretic peptide type-B (NT-proBNP) and troponins (cTn) is used for prognostic stratification. Adrenomedullin is produced by several tissues including the heart, and portends a poor prognosis in heart diseases. We investigated the ability of midregional proadrenomedullin (MR-proADM) to predict early death in AL amyloidosis., Methods: One-hundred and thirty consecutive patients with newly-diagnosed AL amyloidosis were prospectively enrolled. The impact on survival of NT-proBNP, cTnI and MR-proADM was evaluated., Results: The concentration of MR-proADM correlated with systolic and diastolic function, but did not reflect the amount of amyloid deposited in the heart. Moreover, MR-proADM was associated with non-cardiac markers of advanced disease. The staging system based on NT-proBNP and cTnI identified high-risk subjects, but could not discriminate good-risk and intermediate-risk patients. Conversely, a staging system based on MR-proADM and cTnI identified 3 groups with significantly different survivals., Conclusions: Midregional-proADM is a powerful prognostic marker in AL amyloidosis, which may not only reflect cardiac dysfunction but also widespread systemic disease, and can be combined with cTn for detecting patients at risk of early death.