Correlation between a commercial electrophysiological test of sudomotor function and intraepidermal nerve fiber density in hereditary transthyretin amyloidosis.

INTRODUCTION/AIMS: In the early stage, hereditary transthyretin (ATTRv) amyloidosis predominantly affects small nerve fibers, resulting in autonomic dysfunction and impaired sensation of pain and temperature. Evaluation of small fiber neuropathy (SFN) is therefore important for early diagnosis and treatment of ATTRv amyloidosis. Herein, we aimed to investigate the accuracy of a quick and non-invasive commercial sudomotor function test (SFT) for the assessment of SFN in ATTRv amyloidosis. METHODS: We performed the SFT in 39 Japanese adults with ATTRv amyloidosis, and we analyzed the correlations between electrochemical skin conductance (ESC) values obtained via the SFT and the parameters of other neuropathy assessment methods. RESULTS: ESC in the feet demonstrated significant, moderate correlations with intraepidermal nerve fiber density (IENFD) results (Spearman's rank correlation coefficient [rs ], 0.58; p < .002) and other neuropathy assessment methods including the sensory nerve action potential amplitude in the nerve conduction studies (rs , 0.52; p < .001), the Neuropathy Impairment Score (rs , -0.45; p < .01), the heat-pain detection threshold (rs , -0.62; p < .0001), and the autonomic section of the Kumamoto ATTRv clinical score (rs , -0.53; p < .0001). DISCUSSION: In this study, we found that ESC values in the feet via the SFT demonstrated significant, moderate correlations with IENFD and other SFN assessment methods in patients with ATTRv amyloidosis, suggesting that the SFT appears to be an appropriate method for assessment of SFN in this disease.

Disease-Modifying Drugs Extend Survival in Hereditary Transthyretin Amyloid Polyneuropathy.

Hereditary transthyretin (ATTRv) amyloidosis is a rare, fatal systemic disease, associated with polyneuropathy and cardiomyopathy, that is caused by mutant transthyretin (TTR). In addition to liver transplantation, several groundbreaking disease-modifying drugs (DMDs) such as tetrameric TTR stabilizers and TTR gene-silencing therapies have been developed for ATTRv amyloid polyneuropathy. They were based on a working hypothesis of the mechanisms of ATTRv amyloid formation. In this retrospective cohort study, we investigated survival of all 201 consecutive patients with ATTRv amyloidosis in our center. The effects of DMDs on survival improvements were significant not only in early-onset patients but also in late-onset patients. ANN NEUROL 2024;95:230-236.

Popeye Sign in Hereditary Transthyretin Amyloidosis.

This case report describes a 63-year-old man who developed dysesthesia in his feet and was misdiagnosed with chronic inflammatory demyelinating polyradiculoneuropathy.

Binding of serum-derived amyloid-associated proteins to amyloid fibrils.

BACKGROUND: Amyloid signature proteins such as serum amyloid P component, apolipoprotein E (ApoE), and ApoA-IV generally co-localise with amyloid, regardless of the types of amyloid precursor protein or the organs. Most of these proteins derive from serum and have reportedly been involved in amyloid fibril formation and stabilisation, as well as in excretion and degradation of amyloid precursor proteins. However, the processes and mechanisms by which these specific proteins deposit together with amyloid fibrils have not been clarified. METHODS: We analysed the binding of serum proteins to amyloid fibrils derived from amyloid ß and insulin in vitro by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: Specific serum proteins including ApoA-I, ApoE, ApoA-IV, ApoC-III and vitronectin adhered to amyloid fibrils at high concentrations in vitro. In addition, the profile of these proteins commonly occurred in both amyloid ß and insulin amyloid fibrils and was mostly consistent with the composition of amyloid signature proteins. We also showed that high concentrations of serum proteins can adhere to amyloid fibrils in a short time. CONCLUSIONS: Our in vitro results suggest that amyloid signature proteins coexist with amyloid primarily dependent on the binding of each serum protein, in the extracellular fluid, to amyloid fibrils.

Plasma growth differentiation factor 15: a novel tool to detect early changes of hereditary transthyretin amyloidosis.

AIMS: Hereditary transthyretin (ATTRv) amyloidosis is the most frequent and representative form of autosomal dominant hereditary systemic amyloidosis. Disease-modifying treatments of the disease are more effective during the early stages, and we require biomarkers to detect early pathological changes for prompt diagnosis. This study aimed to investigate whether plasma growth differentiation factor 15 (GDF-15) levels could aid detection of early pathological changes in ATTRv amyloidosis. METHODS AND RESULTS: We retrospectively studied 32 patients with ATTRv amyloidosis, eight asymptomatic TTR mutation carriers, and eight healthy volunteers. We evaluated plasma GDF-15 levels in these subjects as related to levels of brain natriuretic peptide and high-sensitivity troponin T, echocardiographic features, 99m Tc-pyrophosphate (PYP) scans, and cardiac magnetic resonance imaging findings. Plasma GDF-15 levels significantly increased even in asymptomatic TTR mutation carriers compared with healthy volunteers (P < 0.01). Plasma GDF-15 levels were significantly correlated with plasma brain natriuretic peptide values (P < 0.01), serum high-sensitivity troponin T values (P < 0.05), and interventricular septal thickness at end-diastole (P < 0.01) in patients with ATTRv amyloidosis. Plasma GDF-15 levels in patients with PYP-positive ATTRv amyloidosis were significantly higher than those in patients with PYP-negative ATTRv amyloidosis (P < 0.01). Plasma GDF-15 levels in patients with late gadolinium enhancement-positive ATTRv amyloidosis were significantly higher than those in patients with late gadolinium enhancement-negative ATTRv amyloidosis (P < 0.01). Groups of patients with different TTR genotypes manifested different plasma GDF-15 levels. CONCLUSIONS: Growth differentiation factor 15 may reflect early pathological changes of ATTRv amyloidosis.

Apolipoprotein AI amyloid deposits in the ligamentum flavum in patients with lumbar spinal canal stenosis.

Amyloidosis is a protein-misfolding disease characterised by insoluble amyloid deposits in the extracellular space of various organs and tissues, such as the brain, heart, kidneys, and ligaments. We previously reported the frequent occurrence of amyloid deposits in the ligament flavum in the presence of lumbar spinal canal stenosis (LSCS), which is a common spinal disorder in older individuals. Our earlier clinicopathological studies revealed that amyloid deposits derived from transthyretin (TTR) were involved in the pathogenesis of LSCS. ATTR amyloid was the most common form in the ligamentum flavum, but amyloid deposits that were not identified still existed in more than 50% of patients with LSCS. In this study, we found apolipoprotein AI (AApoAI) amyloid deposits in the ligamentum flavum of patients with LSCS. The deposits occurred in 12% of patients with LSCS. Biochemical studies revealed that the amyloid deposits consisted mainly of full-length ApoAI. As a notable finding, the lumbar ligamentum flavum of patients who had LSCS with double-positive amyloid deposits-positive for both ATTR and AApoAI-was significantly thicker than that of patients who had LSCS with single-positive-that is, positive for either ATTR or AApoAI-amyloid deposits. We thus suggest that lumbar AApoAI amyloid formation may enhance the pathological changes of lumbar ATTR amyloidosis in patients with LSCS.

Novel dot-blot assay for detection of vascular Notch3 aggregates in patients with CADASIL.

To detect vascular Notch3 extracellular domain aggregates in CADASIL, we developed a novel dot-blot assay with both autopsy and biopsy skin samples. We obtained samples from 11 patients with CADASIL and 12 control patients, and we performed dot-blot analyses by using sequential biochemical tissue extractions with three different antibodies against specific regions of the Notch3 extracellular domain. We also analyzed clinical features and vascular accumulations of Notch3 by immunohistochemistry. Via the dot-blot assay with the antibody against the C-terminal region of the Notch3 extracellular domain, we successfully detected Notch3 extracellular domain aggregates in skin tissue homogenates obtained from patients with CADASIL. Our novel method may therefore aid the diagnosis of CADASIL.

Characteristics of acquired transthyretin amyloidosis: A case series and review of the literature.

OBJECTIVE: To elucidate the clinical characteristics of acquired ATTR amyloidosis after domino liver transplantation (DLT) with liver grafts explanted from patients with hereditary variant ATTR (ATTRv) amyloidosis. METHODS: We evaluated the presence of amyloid deposits and clinical symptoms in 30 recipients of domino liver transplants (24 men and 6 women) who underwent DLT with liver grafts explanted from patients with ATTRv amyloidosis. We analyzed symptoms and measures of 7 cases of symptomatic acquired ATTR amyloidosis and compared those with 30 patients with ATTRv amyloidosis who were the domino liver donors. We also reviewed the literature on case studies of acquired ATTR amyloidosis. RESULTS: We found amyloid deposition in 13 of our 30 domino liver recipients. A Kaplan-Meier analysis estimated that the median time from DLT to the first detection of amyloid was 8.5 years. In the literature review, the mean time was 7.3 years, with a wide range of 0.5-13 years. Our 7 symptomatic cases and the literature cases with acquired ATTR amyloidosis presented with clinical features that differed from patients with ATTRv amyloidosis who were the domino liver donors. Patients with acquired ATTR amyloidosis showed markedly milder autonomic disturbance, which is one of the main symptoms of ATTRv amyloidosis. CONCLUSIONS: Careful monitoring is required for DLT recipients of ATTRv liver grafts because the time from DLT to disease onset has a wide range and the clinical picture of these DLT recipients is distinct from that of liver donors.

Hereditary ATTR Amyloidosis with Cardiomyopathy Caused by the Novel Variant Transthyretin Y114S (p.Y134S).

We report the clinical features of a patient with hereditary transthyretin (ATTR) amyloidosis associated with a novel mutation (Y114S, p.Y134S). A 65-year-old Japanese man was admitted to our hospital after a 3-year history of progressive dyspnea on exertion. Five years previously, he presented dysesthesia in both hands caused by carpal tunnel syndrome. A genetic analysis revealed a base pair substitution of adenine to cytosine in the second codon of exon 4, residue 114, in the TTR gene (c.401A>C). The clinical characteristics were progressive cardiomyopathy with a poor vital prognosis, late onset, sporadic case, bilateral carpal tunnel syndrome, hypothyroidism, and small fiber neuropathy.

A cell-based high-throughput screening method to directly examine transthyretin amyloid fibril formation at neutral pH.

Transthyretin (TTR) is a major amyloidogenic protein associated with hereditary (ATTRm) and nonhereditary (ATTRwt) intractable systemic transthyretin amyloidosis. The pathological mechanisms of ATTR-associated amyloid fibril formation are incompletely understood, and there is a need for identifying compounds that target ATTR. C-terminal TTR fragments are often present in amyloid-laden tissues of most patients with ATTR amyloidosis, and on the basis of in vitro studies, these fragments have been proposed to play important roles in amyloid formation. Here, we found that experimentally-formed aggregates of full-length TTR are cleaved into C-terminal fragments, which were also identified in patients' amyloid-laden tissues and in SH-SY5Y neuronal and U87MG glial cells. We observed that a 5-kDa C-terminal fragment of TTR, TTR81-127, is highly amyloidogenic in vitro, even at neutral pH. This fragment formed amyloid deposits and induced apoptosis and inflammatory gene expression also in cultured cells. Using the highly amyloidogenic TTR81-127 fragment, we developed a cell-based high-throughput screening method to discover compounds that disrupt TTR amyloid fibrils. Screening a library of 1280 off-patent drugs, we identified two candidate repositioning drugs, pyrvinium pamoate and apomorphine hydrochloride. Both drugs disrupted patient-derived TTR amyloid fibrils ex vivo, and pyrvinium pamoate also stabilized the tetrameric structure of TTR ex vivo in patient plasma. We conclude that our TTR81-127-based screening method is very useful for discovering therapeutic drugs that directly disrupt amyloid fibrils. We propose that repositioning pyrvinium pamoate and apomorphine hydrochloride as TTR amyloid-disrupting agents may enable evaluation of their clinical utility for managing ATTR amyloidosis.

New simple and quick method to analyze serum variant transthyretins: direct MALDI method for the screening of hereditary transthyretin amyloidosis.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is caused by a variant transthyretin (TTR), which is a serum protein secreted by the liver. Mass spectrometry (MS) is a useful tool that can detect variant TTRs in serum samples from patients with ATTRv amyloidosis. We previously reported several mass spectrometric methods to detect variant TTRs in serum samples. Those methods require cumbersome immunoprecipitation with anti-TTR antibodies and significant time to analyze the variant TTRs. In our study here, we developed a new simple and quick method to detect variant TTRs in serum samples by means of matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) MS without immunoprecipitation (direct MALDI). METHODS: By using direct MALDI, we analyzed 288 serum samples obtained from patients who were clinically suspected having amyloidosis to investigate the usefulness of this direct MALDI method to detect variant TTRs in serum samples. RESULTS: The method completed the process within 30 min. We successfully identified variant TTRs in serum samples from patients, except for a few patients with TTR Glu61Lys and Glu89Gln mutations because of the small mass shift of those variant TTRs from wild-type TTR. We also found that the mass shifts of variant TTRs measured by direct MALDI corresponded to theoretical mass changes. CONCLUSION: Our results suggest that the direct MALDI method is useful for the screening of ATTRv amyloidosis.

Extreme Adhesion Activity of Amyloid Fibrils Induces Subcutaneous Insulin Resistance.

Insulin-derived amyloidoma, also called an insulin ball, is a skin-related complication of insulin therapy caused by repeated insulin injections at the same site, where native folded insulin changes into amyloid fibrils and forms a mass with a granulomatous reaction. Insulin-derived amyloidoma is a clinically important condition because of its association with subcutaneous insulin resistance, but the precise effect and mechanism of the insulin absorption impairment have not been clarified. We generated insulin-derived amyloidomas in mouse skin, with the amyloidomas large enough to perform insulin tolerance tests in the mass by repeated injections of highly concentrated insulin amyloid fibrils. We demonstrated that the insulin-derived amyloidomas inhibit insulin absorption. By simultaneous administration of insulin and insulin amyloid fibrils, we showed that this effect is due to the amyloid fibril itself in the absence of a granulomatous reaction. In vitro studies revealed that insulin amyloid fibrils have extremely strong adhesion to native human insulin and various insulin analogs. Furthermore, we showed that native insulin that had adhered to insulin amyloid forms amyloid fibrils at physiological pH. These results suggest that the extreme adhesion of insulin amyloid to native insulin is the main mechanism of impaired insulin absorption and amyloidoma growth.

A novel age-related venous amyloidosis derived from EGF-containing fibulin-like extracellular matrix protein 1.

Most intractable tissue-degenerative disorders share a common pathogenic condition, so-called proteinopathy. Amyloid-related disorders are the most common proteinopathies and are characterized by amyloid fibril deposits in the brain or other organs. Aging is generally associated with the development of these amyloid-related disorders, but we still do not fully understand how functional proteins become pathogenic amyloid deposits during the human aging process. We identified a novel amyloidogenic protein, named epidermal growth factor-containing fibulin-like extracellular matrix protein 1 (EFEMP1), in massive venous amyloid deposits in specimens that we obtained from an autopsied patient who died of gastrointestinal bleeding. Our postmortem analyses of additional patients indicate that EFEMP1 amyloid deposits frequently developed in systemic venous walls of elderly people. EFEMP1 was highly expressed in veins, and aging enhanced venous EFEMP1 expression. In addition, biochemical analyses indicated that these venous amyloid deposits consisted of C-terminal regions of EFEMP1. In vitro studies showed that C-terminal regions formed amyloid fibrils, which inhibited venous tube formation and cell viability. EFEMP1 thus caused a novel age-related venous amyloid-related disorder frequently found in the elderly population. Understanding EFEMP1 amyloid formation provides new insights into amyloid-related disorders occurring during the aging process. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.