Transthyretin valine-94-alanine, a novel variant associated with late-onset systemic amyloidosis with cardiac involvement.

A 63-year-old Caucasian male, diagnosed with dilated cardiomyopathy in 1993, remained clinically stable for several years. In 2003, a marked increase of N-terminal pro-natriuretic peptide serum level (611 ng/ml to 4926 ng/ml) was observed; left ventricular (LV) septum thickness was 10 mm. In addition, sensorimotor polyneuropathy and autonomic dysfunction occurred. Further progression of heart failure occurred despite unchanged systolic LV function. Endomyocardial biopsy in 2006 revealed transthyretin amyloidosis by Congo red and immunohistochemical staining, as well as Val94Ala substitution by transthyretin gene analysis. Cardiac amyloid deposition was quantified by technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy. Mutational search of the relatives (n = 1) was unremarkable. The transthyretin Val94Ala mutation is characterized by sensorimotor polyneuropathy, autonomic dysfunction, and gastrointestinal and cardiac involvement with amyloid. This mutation is an addition to the growing spectrum of transthyretin mutations with late onset of clinical symptoms, but noteworthy because of progressive, finally disabling disease course. Final clinical assessment of severity of cardiac involvement in the present patient is rendered complex by possible concomitant or preceding idiopathic dilated cardiomyopathy.

Indications for liver transplantation in patients with amyloidosis: a single-center experience with 11 cases.

Familial amyloidotic polyneuropathy (FAP) is an inherited disorder with the systemic deposition of amyloid fibrils containing mutant transthyretin variants. The mutant form of transthyretin amyloidosis is produced mainly in the liver. Successful liver transplantation (LTx) could eliminate the source of the variant transthyretin molecule, and is now the only known curative treatment. The aim of this study is to evaluate the results of LTx for FAP at the University of Heidelberg. Eleven patients who underwent LTx between 1985 and 2004 with the diagnosis of FAP were evaluated. Of 11 patients, seven (64%) were male and four (36%) were female. The mean age was 49.5 years (range 27-70). Met 30 (n=5) was the most common type of amyloidosis followed by Arg 50 (n=3), Val 107 (n=2), and Phe 33 (n=1). All of the patients were selected for LTx and Domino LTx was performed in six patients. The majority (80%) of the patients with type Met 30 amyloidosis are alive, whereas in other types of amyloidosis only 33% are living. This finding emphasizes better prognosis of Met 30 variant of FAP in comparison to other variants such as Arg 50, Val 107, and Phe 33. After LTx, improvement of clinical symptoms (completely or partially) was observed in six patients (55%). In conclusion, LTx is considered as the only therapeutic alternative in patients with amyloidosis accompanied by hepatic synthesis of the amyloid protein. The most important risk factors for LTx can be predicted by assessing the nutritional condition of the patient, the duration of the disease, and the amyloid variant. Therefore, precise diagnostic measures are required before listing a patient for LTx. Domino LTx is an acceptable form of LTx that can preserve the pool of organ donors. In order to stop the progression of FAP, LTx would be justified in a subgroup of patients with amyloidosis. Based on our results, we support the idea that the effectiveness of extended preoperative period before LTx or the transplantation of other transthyretin variants other than Met 30 is questionable.

Green tea extract as a treatment for patients with wild-type transthyretin amyloidosis: an observational study.

BACKGROUND: Causative treatment of patients with wild-type transthyretin amyloid cardiomyopathy (wtATTR-CM) is lacking. Recent reports indicate the potential use of epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea, to inhibit amyloid fibril formation. We sought to investigate changes of cardiac function and morphology in patients with wtATTR-CM after consumption of green tea extract (GTE). METHODS: Twenty-five male patients (71 [64; 80] years) with wtATTR-CM were submitted to clinical examination, echocardiography, cardiac magnetic resonance imaging (cMRI) (n=14), and laboratory testing before and after daily consumption of GTE capsules containing 600 mg epigallocatechin-3-gallate for at least 12 months. RESULTS: A significant decrease of left ventricular (LV) myocardial mass by 6% (196 [100; 247] vs 180 [85; 237] g; P=0.03) by cMRI and total cholesterol by 8.4% (191 [118; 267] vs 173 [106; 287] mg/dL; P=0.006) was observed after a 1-year period of GTE consumption. LV ejection fraction by cMRI (53% [33%; 69%] vs 54% [28%; 71%]; P=0.75), LV wall thickness (17 [13; 21] vs 18 [14; 25] mm; P=0.1), and mitral annular plane systolic excursion (10 [5; 23] vs 8 [4; 13] mm; P=0.3) by echocardiography remained unchanged. CONCLUSION: This study supports LV mass stabilization in patients with wtATTR-CM consuming GTE potentially indicating amyloid fibril reduction.

Skeletal scintigraphy indicates disease severity of cardiac involvement in patients with senile systemic amyloidosis.

BACKGROUND: Senile systemic amyloidosis (SSA) is a common aging phenomenon in the elderly population. Nevertheless, pre-mortem diagnosis of SSA is rare. Thus, data on clinical characterization and disease severity are limited. METHODS: 36 consecutive SSA patients (71.6 [64.7-82.7]years) were evaluated by electrocardiography, echocardiography, laboratory tests, and (99m)Technetium-3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) scintigraphy (n=20). RESULTS: In addition to cardiac involvement, amyloid deposition was found in rectum (n=6), peripheral nerves (n=2), and urinary bladder (n=2). Five patients showed low voltage pattern. Thickness of interventricular septum (IVS) was 20 [12-27]mm. LV longitudinal function was diminished (TDI-s 5 [3-11] cm/s; MAPSE 6.5 [2.5-19]mm; TAPSE 12.5 [2-24]mm). LV systolic function (LV-EF<45%) was markedly decreased in 19 patients. Plasma levels of troponin T (0.05 [0.01-0.23]µg/L) and NT-proBNP (4318 [205-16597]ng/L) were elevated. (99m)Tc-DPD heart retention was 7.8 [2.4-11.0]% and correlated with MAPSE (ρ=-0.716; p=0.0018), TAPSE (ρ=-0.491; p<0.05), and IVS (ρ=0.556; p=0.0153). Heart-to-body ratio correlated with MAPSE (ρ=-0.771; p=0.0018), IVS (ρ=0.603; p=0.0086). Twelve patients died during follow-up of 27.4 [0.1-106.2]months. Exclusively (99m)Tc-DPD heart retention, diastolic dysfunction and in trend MAPSE were associated with patient's outcome. Interestingly, risk predictors that were well established in patients with AL amyloidosis were not predictive for survival in patients with SSA. CONCLUSIONS: This study gave first evidence that (99m)Tc-DPD HR may be capable to display the extent of cardiac amyloid deposition. Moreover, this study suggested that (99m)Tc-DPD HR, diastolic dysfunction and in trend MAPSE are associated with poor outcome. Nevertheless, these findings need to be established in a larger prospective trial.

Green tea halts progression of cardiac transthyretin amyloidosis: an observational report.

BACKGROUND: Treatment options in patients with amyloidotic transthyretin (ATTR) cardiomyopathy are limited. Epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea (GT), inhibits fibril formation from several amyloidogenic proteins in vitro. Thus, it might also halt progression of TTR amyloidosis. This is a single-center observational report on the effects of GT consumption in patients with ATTR cardiomopathy. METHODS: 19 patients with ATTR cardiomyopathy were evaluated by standard blood tests, echocardiography, and cardiac MRI (n = 9) before and after consumption of GT and/or green tea extracts (GTE) for 12 months. RESULTS: Five patients were not followed up for reasons of death (n = 2), discontinuation of GT/GTE consumption (n = 2), and heart transplantation (n = 1). After 12 months no increase of left ventricular (LV) wall thickness and LV myocardial mass was observed by echocardiography. In the subgroup of patients evaluated by cardiac MRI a mean decrease of LV myocardial mass (-12.5 %) was detected in all patients. This was accompanied by an increase of mean mitral annular systolic velocity of 9 % in all 14 patients. Total cholesterol (191.9 ± 8.9 vs. 172.7 ± 9.4 mg/dL; p < 0.01) and LDL cholesterol (105.8 ± 7.6 vs. 89.5 ± 8.0 mg/dL; p < 0.01) decreased significantly during the observational period. No serious adverse effects were reported by any of the participants. CONCLUSIONS: Our observation suggests an inhibitory effect of GT and/or GTE on the progression of cardiac amyloidosis. We propose a randomized placebo-controlled investigation to confirm our observation.

Restrictive cardiomyopathy in inherited ATTR amyloidosis (TTR-Ser23Asn) in a patient of German-Italian extraction.

Amyloidosis occurs when certain soluble proteins are transformed into amyloid fibrils in the extracellular space. Most common are the light-chain amyloidoses; less common is the AA-amyloidosis, which follows chronic inflammatory diseases, and the amyloidoses of transthyretin (TTR) origin. We report on a women of Italian-German origin with the mutation TTR (Ser23Asn). Whole body scintigraphy using TC99m-DPD showed end stage hereditary amyloidosis caused by ATTR with predominant tracer retention in the myocardium. Myocardial biopsies revealed the presence of amyloid by Congo red staining. Further immunohistochemical analysis showed ATTR amyloidosis. DNA sequencing revealed a point mutation of the transthyretin gene leading to a single amino acid substitution. The only effective treatment in patients with manifest cardiac ATTR amyloidosis is combined heart and liver transplantation. Our patient was placed on a list for this procedure, but unfortunately she died during the standby procedure due to urosepsis.

Genetic microheterogeneity of human transthyretin detected by IEF.

Mutations of the human transthyretin (TTR) gene have attracted medical interest as a cause of amyloidosis. Recently, we have described in detail an electrophoretic procedure with PAGE followed by IEF in urea gradients for the study of the microheterogeneity of TTR monomers (Altland, K., Winter, P., Sauerborn, M. K., Electrophoresis 1999, 20, 1349-1364). In this paper, we present a study on 49 different mutations of TTR including 33 that result in electrically neutral amino acid substitutions. The aims of the investigation were to test the sensitivity of the procedure to detect TTR variants in patients with TTR amyloidosis and their relatives and to identify some common characteristics that could explain the amyloidogenicity of these variants. We found that all tested amyloidogenic mutations could be detected by our method with the exception of those for which the corresponding variant was absent in plasma samples. Most of the electrically neutral amyloidogenic TTR variants had in common a reduced conformational stability of monomers by the activity of protons and urea. For three variants, e.g. TTR-F64L, TTR-I107V and TTR-V122I, the monomers had a conformational stability close to that of normal monomers but we found experimental and structural arguments for a weakening of the monomer-monomer contact. All types of amyloidogenic mutations affected the stability of TTR tetramers.

Polyacrylamide gel electrophoresis followed by sodium dodecyl sulfate gradient polyacrylamide gel electrophoresis for the study of the dimer to monomer transition of human transthyretin.

Familial amyloidotic polyneuropathy (FAP) is caused by mutations which destabilize transthyretin (TTR) and facilitate the aggregation into extracellular amyloid fibrils preferentially in peripheral nerve and heart tissues. Therapeutic and preventive trials for FAP at the plasma TTR level require a careful study of the destabilization of TTR under variable conditions. We have developed a simple double one-dimensional (D1-D) electrophoretic procedure with polyacrylamide gel electrophoresis (PAGE) followed by sodium dodecylsulfate (SDS) gradient PAGE to study the dimer to monomer transition. TTR is first isolated by PAGE from other plasma proteins. The gel strip containing the TTR fraction is incubated in 2% SDS under varying conditions of temperature, buffer composition, pH, and additives like urea and/or a sulfhydryl-reactive agent, followed by SDS-gradient PAGE for the separation of TTR dimers and monomers. We demonstrate that an unidirectional dimer to monomer transition of normal TTR is achieved at 70-80 degrees C in neutral to mild alkaline buffers or at 37 degrees C and slightly acidic pH (6-7). Addition of urea favors the transition into monomers. Amyloidogenic mutations like amyloidogenic TTR (ATTR)-V30M or ATTR-I107V favor the transition into monomers in buffer systems close to the physiological pH of human plasma. We conclude that this finding has to be considered by any hypothesis on ATTR-derived amyloidogenesis.

Sulfite and base for the treatment of familial amyloidotic polyneuropathy: two additive approaches to stabilize the conformation of human amyloidogenic transthyretin.

Recently, we presented evidence that sulfite protects transthyretin (TTR) from normal human individuals and heterozygotes with amyloidogenic TTR mutations against the decay of tetramers into monomers. In this paper we demonstrate a stabilizing effect of sulfite on TTR tetramers from a familial amyloidotic polyneuropathy (FAP) patient homozygous for the most-common amyloidogenic TTR-V30 M mutation. We compare the conformational stability of partially sulfonated TTR from a heterozygote for normal TTR and amyloidogenic TTR-V30 M with the stability of untreated TTR from a compound heterozygote for amyloidogenic TTR-V30 M and TTR-T119 M known to have only minor or no problems of FAP. Using a combination of polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS) gradient PAGE we demonstrate that TTR dimers containing amyloidogenic TTR mutations decay into monomers at pH<7.4. Increasing the pH by some 0.2 units within physiological ranges, i.e., pH 7.0-7.4, and sulfonation of TTR were observed to have additive inhibitory effects on the transition of dimers into monomers. We conclude that mild acidifying episodes in the interstitial volume of tissues at risk for amyloidosis could contribute to the development of FAP. Early and permanent efforts to counteract acidosis by treatment with base could possibly help to delay the onset of the disease. The intake of sulfite could support these efforts.

99mTc-DPD scintigraphy in transthyretin-related familial amyloidotic polyneuropathy.

Familial amyloidotic polyneuropathy (FAP) caused by amyloidogenic transthyretin (ATTR) mutations is the most common form of hereditary amyloidosis. We investigated the diagnostic value of the bone scanning agent technetium-99m 3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) in this disease. Eight patients (four males, four females; age 54.4+/-8.3 years, range 43-67 years) with ATTR-FAP proven by immunohistochemistry and molecular analysis and a control group comprising ten oncological out-patients (five males, five females; age 53.4+/-8.5 years, range 34-66 years) without evidence of bony metastases were studied using 99mTc-DPD. Whole body tracer retention was 80.1%+/-10.3% (range 65.1%-94.8%) in FAP patients and 55.7%+/-8.1% (range 40.2%-66.7%) in controls at 3 h p.i. (P<0.001), and cardiac uptake was 7.3%+/-2.2% (range 4.2%-10.1%) in FAP patients and 3.1%+/-0.5% (range 2.3%-4.0%) in controls (P<0.001). The heart/whole body uptake ratio was 8.9%+/-1.7% (range 6.5%-11.0%) in FAP patients and 5.6%+/-0.5% (range 5.1%-6.8%) in controls (P<0.001). The three FAP patients with the highest cardiac tracer uptake had cardiomyopathy or arrhythmia. 99mTc-DPD scintigraphy is proposed as a simple and valuable diagnostic aid to evaluate the severity of the disease and the risk of concomitant heart problems.

D18G transthyretin is monomeric, aggregation prone, and not detectable in plasma and cerebrospinal fluid: a prescription for central nervous system amyloidosis?

Over 70 transthyretin (TTR) mutations facilitate amyloidosis in tissues other than the central nervous system (CNS). In contrast, the D18G TTR mutation in individuals of Hungarian descent leads to CNS amyloidosis. D18G forms inclusion bodies in Escherichia coli, unlike the other disease-associated TTR variants overexpressed to date. Denaturation and reconstitution of D18G from inclusion bodies afford a folded monomer that is destabilized by 3.1 kcal/mol relative to an engineered monomeric version of WT TTR. Since TTR tetramer dissociation is typically rate limiting for amyloid formation, the monomeric nature of D18G renders its amyloid formation rate 1000-fold faster than WT. It is perplexing that D18G does not lead to severe early onset systemic amyloidosis, given that it is the most destabilized TTR variant characterized to date, more so than variants exhibiting onset in the second decade. Instead, CNS impairment is observed in the fifth decade as the sole pathological manifestation; however, benign systemic deposition is also observed. Analysis of heterozygote D18G patient's serum and cerebrospinal fluid (CSF) detects only WT TTR, indicating that D18G is either rapidly degraded postsecretion or degraded within the cell prior to secretion, consistent with its inability to form hybrid tetramers with WT TTR. The nondetectable levels of D18G TTR in human plasma explain the absence of an early onset systemic disease. CNS disease may result owing to the sensitivity of the CNS to lower levels of D18G aggregate. Alternatively, or in addition, we speculate that a fraction of D18G made by the choroid plexus can be transiently tetramerized by the locally high thyroxine (T(4)) concentration, chaperoning it out into the CSF where it undergoes dissociation and amyloidogenesis due to the low T(4) CSF concentration. Selected small molecule tetramer stabilizers can transform D18G from a monomeric aggregation-prone state to a nonamyloidogenic tetramer, which may prove to be a useful therapeutic strategy against TTR-associated CNS amyloidosis.