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Concept: Transthyretin

177

Amyloidosis of the gastrointestinal tract, with biopsy-proven disease, is rare. We reviewed a series of patients who presented with biopsy-proven gastrointestinal amyloidosis and report their clinical characteristics, treatments, and survival. This is a retrospective review of data prospectively collected from January 1998 to December 2011 in a tertiary referral center; 2,334 patients with all types of amyloidosis were evaluated during this period. Seventy-six patients (3.2%) had biopsy-proven amyloid involvement of the gastrointestinal tract. Their median age was 61 years (range, 34-79). Systemic amyloidosis with dominant gastrointestinal involvement was present in 60 (79%) patients, whereas the other 16 (21%) patients had amyloidosis localized to the gastrointestinal tract without evidence of an associated plasma cell dyscrasia or other organ involvement. Of the 60 systemic cases, 50 (83%) had immunoglobulin light-chain, five (8%) had familial lysozyme, three (5%) had wild-type transthyretin, and two (3%) had mutant transthyretin amyloidosis. The most frequent symptoms for all patients were weight loss in 33 (45%) and gastrointestinal bleeding in 27 (36%). Incidental identification of amyloidosis on routine endoscopic surveillance played a role in the diagnosis of seven patients with systemic immunoglobulin light-chain, and four patients with immunoglobulin light-chain localized to the gastrointestinal tract. Amyloid protein subtyping was performed in 12 of the cases of localized disease, and all had lambda light chain disease. Of the 50 patients with systemic immunoglobulin light-chain amyloidosis, 45 were treated with anti-plasma cell therapy. The median survival has not been reached for this group. For the 16 patients with localized gastrointestinal amyloidosis, supportive care was the mainstay of treatment; none received anti-plasma cell therapy. All 16 are alive at a median follow-up of 36 months (range, 1-143). Patients with biopsy-proven gastrointestinal amyloidosis often present with weight loss and bleeding. In localized cases, all that underwent typing were due to lambda light chain amyloidosis and none progressed to systemic disease during the period of follow-up. Most patients with systemic disease had immunoglobulin light-chain, and their tolerance of therapy and median survival were excellent. Although a rare manifestation of amyloidosis, staining for amyloid should be considered in patients undergoing gastrointestinal biopsy who have unexplained chronic gastrointestinal symptoms.

Concepts: Congo red, Transthyretin, Multiple myeloma, Immunoglobulin light chain, Protein, Diseases and disorders, Amyloid, Amyloidosis

144

Transthyretin-related familial amyloid polyneuropathy (TTR-FAP) typically arises as an autonomic neuropathy primarily affecting small fibres and it occurs in adult patients in their second or third decades of life. It progresses rapidly and can lead to death in approximately 10 years. Other phenotypes have been described in non-endemic areas.

Concepts: Area, Evolution, Life, Transthyretin, Amyloid, Amyloidosis, Neurological disorders, Familial amyloid polyneuropathy

28

Misfolded and aggregated transthyretins (agTTR) contribute to neurodegenerative amyloid diseases such as familial amyloid polyneuropathy and senile systemic amyloidosis. The neurotoxicity mechanisms of agTTR, however, are not well understood. In the current study, the possible contribution of reactive nitrogen species (RNS) to such mechanisms was investigated by examining agTTR-mediated changes in cellular RNS levels.

Concepts: The Current, Neurology, Senile systemic amyloidosis, Diseases and disorders, Familial amyloid polyneuropathy, Transthyretin, Amyloid, Amyloidosis

28

The transthyretin amyloidoses (ATTR) are devastating diseases characterized by progressive neuropathy and/or cardiomyopathy for which novel therapeutic strategies are needed. We have recently shown that curcumin (diferuloylmethane), the major bioactive polyphenol of turmeric, strongly suppresses TTR fibril formation in vitro, either by stabilization of TTR tetramer or by generating nonfibrillar small intermediates that are innocuous to cultured neuronal cells. In the present study, we aim to assess the effect of curcumin on TTR amyloidogenesis in vivo, using a well characterized mouse model for familial amyloidotic polyneuropathy (FAP). Mice were given 2% (w/w) dietary curcumin or control diet for a six week period. Curcumin supplementation resulted in micromolar steady-state levels in plasma as determined by LC/MS/MS. We show that curcumin binds selectively to the TTR thyroxine-binding sites of the tetramer over all the other plasma proteins. The effect on plasma TTR stability was determined by isoelectric focusing (IEF) and curcumin was found to significantly increase TTR tetramer resistance to dissociation. Most importantly, immunohistochemistry (IHC) analysis of mice tissues demonstrated that curcumin reduced TTR load in as much as 70% and lowered cytotoxicity associated with TTR aggregation by decreasing activation of death receptor Fas/CD95, endoplasmic reticulum (ER) chaperone BiP and 3-nitrotyrosine in tissues. Taken together, our results highlight the potential use of curcumin as a lead molecule for the prevention and treatment of TTR amyloidosis.

Concepts: Curcumin, In vivo, In vitro, Amyloid, Transthyretin, Amyloidosis, Endoplasmic reticulum, Protein

28

Introduction: Information related to the long-term follow-up of neuropathy in patients with familial amyloid polyneuropathy after liver transplantation is still scarce. Methods: We describe the neuropathic features of 3 patients with the transthyretin Val30Met mutation. Each patient underwent liver transplantation at an early stage of neuropathy, as indicated by the absence of motor dysfunction and relative preservation of myelinated fibers in sural nerve biopsy specimens. Results: Although the patient with late-onset disease (at age 60 years) presented with the least amount of amyloid deposition, he had neuropathic progression after liver transplantation. An older early-onset (at age 40 years) patient reported a slight exacerbation of both somatic and autonomic neuropathic symptoms 10 years after transplantation. However, the younger early-onset (at age 28 years) patient did not exhibit characteristics suggestive of neuropathy 7 years after transplantation. Conclusion: Aging may determine the progression of neuropathy after liver transplantation. Muscle Nerve, 2012.

Concepts: Cancer, Transthyretin, Sural nerve, Amyloidosis, Patient, Nervous system, Familial amyloid polyneuropathy, Amyloid

28

Background: Transthyretin (TTR) amyloidosis is a rare, life-threatening, systemic, autosomal dominant condition occurring in adults, with two main forms: hereditary (associated with TTR gene mutations) and wild-type. Studies indicate considerable heterogeneity in disease presentation, with predominantly polyneuropathic, predominantly cardiac, or mixed phenotypes. Methods: THAOS - the Transthyretin Amyloidosis Outcomes Survey - is the first global, multicenter, longitudinal, observational survey that collects data on the natural history of TTR amyloidosis (ClinicalTrials.gov: NCT00628745). This paper presents data on signs and symptoms, neurological and cardiac assessments, biomarkers and quality of life in the patients enrolled in THAOS from its inception in December 2007 to September 2011. Results: At the time of this analysis, data were available from 611 symptomatic patients with hereditary TTR amyloidosis, 67 symptomatic patients with wild-type TTR amyloidosis, and 274 currently asymptomatic individuals with a TTR mutation. Nineteen countries were participating in the registry. The largest patient groups came from Portugal (n=453), the USA (n=129), Italy (n=70), and Japan (n=68). Predominant symptom presentation in patients with hereditary TTR amyloidosis differed according to the underlying disease-causing mutation (polyneuropathy for Val30Met, cardiomyopathy for Val122Ile and Leu111Met, and mixed for Glu89Gln). However, each mutation was associated with clear multisystem involvement. Similarly, although cardiomyopathy was predominant in patients with wild-type TTR amyloidosis, many also showed symptoms consistent with neuropathy. Quality of life in patients with hereditary TTR amyloidosis, but not asymptomatic carriers of disease-causing mutations, was severely impaired relative to that of the age-matched general US population. Conclusions: This preliminary analysis highlights the considerable phenotypic heterogeneity for neurological and cardiac manifestations in patients with hereditary and wild-type TTR amyloidosis and the necessity of providing multidisciplinary care. THAOS registry data will help better characterize the diverse presentation and course of TTR amyloidosis worldwide and aid in improving and standardizing diagnosis and treatment.

Concepts: Evolution, Symptom, Transthyretin, Windows Registry, Gene, Mutation, Phenotype, Natural selection

28

The transthyretin amyloidoses (ATTR) are invariably fatal diseases characterized by progressive neuropathy and/or cardiomyopathy. ATTR are caused by aggregation of transthyretin (TTR), a natively tetrameric protein involved in the transport of thyroxine and the vitamin A-retinol-binding protein complex. Mutations within TTR that cause autosomal dominant forms of disease facilitate tetramer dissociation, monomer misfolding, and aggregation, although wild-type TTR can also form amyloid fibrils in elderly patients. Because tetramer dissociation is the rate-limiting step in TTR amyloidogenesis, targeted therapies have focused on small molecules that kinetically stabilize the tetramer, inhibiting TTR amyloid fibril formation. One such compound, tafamidis meglumine (Fx-1006A), has recently completed Phase II/III trials for the treatment of Transthyretin Type Familial Amyloid Polyneuropathy (TTR-FAP) and demonstrated a slowing of disease progression in patients heterozygous for the V30M TTR mutation. Herein we describe the molecular and structural basis of TTR tetramer stabilization by tafamidis. Tafamidis binds selectively and with negative cooperativity (K(d)s ~2 nM and ~200 nM) to the two normally unoccupied thyroxine-binding sites of the tetramer, and kinetically stabilizes TTR. Patient-derived amyloidogenic variants of TTR, including kinetically and thermodynamically less stable mutants, are also stabilized by tafamidis binding. The crystal structure of tafamidis-bound TTR suggests that binding stabilizes the weaker dimer-dimer interface against dissociation, the rate-limiting step of amyloidogenesis.

Concepts: Monomer, Tetramer, Familial amyloid polyneuropathy, Stabilization, Transthyretin, Amyloid, Stabilizer

27

Amyloidosis is a rare disease in which insoluble extracellular protein fibrils in β-pleated sheets infiltrate multiple organs, causing organ dysfunction and failure. Amyloidoses are generally classified into light chain or primary systemic amyloidosis, hereditary amyloidosis (most commonly, transthyretin amyloidosis), senile systemic amyloidosis, secondary amyloidosis, and isolated atrial amyloidosis. At least 100 different amyloidogenic proteins have been identified in humans and can be differentiated by mass spectroscopy after laser capture microdissection and genetic testing. Organ involvement can include kidneys, skin, blood vessels, central and peripheral nervous systems, lungs, liver, intestines, and heart. Developments in noninvasive techniques are facilitating earlier and more accurate diagnosis. Management depends on the specific disease type, thus early and accurate diagnosis is imperative. Prognosis generally correlates with degree of cardiac involvement but varies widely with specific amyloid protein type. New treatment strategies involving chemotherapy and organ transplantation are improving survival, but prognosis is guarded.

Concepts: Beta sheet, Prion, Organ, Transthyretin, Blood, Amyloid, Heart, Amyloidosis

25

Early and accurate diagnosis of transthyretin familial amyloid polyneuropathy (TTR-FAP) represents one of the major challenges faced by physicians when caring for patients with idiopathic progressive neuropathy. There is little consensus in diagnostic and management approaches across Europe.

Concepts: Sweden, Neurological disorders, Physician, Transthyretin, Medical terms, Familial amyloid polyneuropathy

6

Transthyretin amyloidosis (ATTR amyloidosis) is caused by the misfolding and deposition of the transthyretin (TTR) protein and results in progressive multi-organ dysfunction. TTR epitopes exposed by dissociation and misfolding are targets for immunotherapeutic antibodies. We developed and characterized antibodies that selectively bound to misfolded, non-native conformations of TTR.

Concepts: Senile systemic amyloidosis, Transthyretin, Monoclonal antibodies, Immunology, Antigen, Immune system, Antibody, Amyloid