Extracardiac 18F-florbetapir imaging in patients with systemic amyloidosis: more than hearts and minds.

PURPOSE: 18F-Florbetapir has been reported to show cardiac uptake in patients with systemic light-chain amyloidosis (AL). This study systematically assessed uptake of 18F-florbetapir in patients with proven systemic amyloidosis at sites outside the heart. METHODS: Seventeen patients with proven cardiac amyloidosis underwent 18F-florbetapir PET/CT imaging, 15 with AL and 2 with transthyretin amyloidosis (ATTR). Three patients had repeat scans. All patients had protocolized assessment at the UK National Amyloidosis Centre including imaging with 123I-serum amyloid P component (SAP). 18F-Florbetapir images were assessed for areas of increased tracer accumulation and time-uptake curves in terms of standardized uptake values (SUVmean) were produced. RESULTS: All 17 patients showed 18F-florbetapir uptake at one or more extracardiac sites. Uptake was seen in the spleen in 6 patients (35%; 6 of 9, 67%, with splenic involvement on 123I-SAP scintigraphy), in the fat in 11 (65%), in the tongue in 8 (47%), in the parotids in 8 (47%), in the masticatory muscles in 7 (41%), in the lungs in 3 (18%), and in the kidney in 2 (12%) on the late half-body images. The 18F-florbetapir spleen retention index (SRI) was calculated. SRI >0.045 had 100% sensitivity/sensitivity (in relation to 123I-SAP splenic uptake, the current standard) in detecting splenic amyloid on dynamic imaging and a sensitivity of 66.7% and a specificity of 100% on the late half-body images. Intense lung uptake was seen in three patients, one of whom had lung interstitial infiltration suggestive of amyloid deposition on previous high-resolution CT. Repeat imaging showed a stable appearance in all three patients suggesting no early impact of treatment response. CONCLUSION: 18F-Florbetapir PET/CT is a promising tool for the detection of extracardiac sites of amyloid deposition. The combination of uptake in the heart and uptake in the spleen on 18F-florbetapir PET/CT, a hallmark of AL, suggests that this tracer holds promise as a screening tool for AL.

A study of the neuropathy associated with transthyretin amyloidosis (ATTR) in the UK.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTR) is usually characterised by a progressive peripheral and autonomic neuropathy often with associated cardiac failure and is due to dominantly inherited transthyretin mutations causing accelerated amyloid deposition. The UK population is unique in that the majority of patients have the T60A missense mutation in ATTR where tyrosine is replaced by adenine at position 60. This has been traced to a single founder mutation from north-west Ireland. The neuropathy phenotype is less well described than the cardiac manifestations in this group. METHODS: We present the findings from an observational cohort study of patients with ATTR attending the National Hospital Inherited Neuropathy Clinic between 2009 and 2013. Detailed clinical neurological and electrophysiological data were collected on all patients alongside correlating autonomic and cardiac assessments. Follow-up data were available on a subset. RESULTS: Forty-four patients with genetically confirmed ATTR were assessed; 37 were symptomatic; mean age at onset=62 years, range=38-75 years; 75.7% male. T60A was the most common mutation (17/37), followed by V30M (5/37). A severe, rapidly progressive, predominantly length dependent axonal sensorimotor neuropathy was the predominant phenotype. T60A patients were distinguished by earlier and more frequent association with carpal tunnel syndrome; a predominance of negative sensory symptoms at onset; significant vibration deficits; and a non-length dependent progression of motor deficit. Progression of the neuropathy was observed over a relatively short follow-up period (2 years) in 20 patients with evidence of clinically measurable annual change in Medical Research Council (MRC) sum score (-1.5 points per year) and Charcot Marie Tooth Neuropathy Score (CMTNS:2.7 points per year), and a congruent trend in the electrophysiological measures used. CONCLUSION: The description of the ATTR neuropathy phenotype, especially in the T60A patients, should aid early diagnosis as well as contribute to the understanding of its natural history.

Neurology of the cryopyrin-associated periodic fever syndrome.

BACKGROUND AND PURPOSE: The cryopyrin-associated periodic fever syndrome (CAPS) is an autosomal dominant autoinflammatory disorder caused by mutations in the NLRP3 gene and is typified by recurrent episodes of systemic inflammation resulting in fever, urticarial rash and arthralgia. In addition to these systemic aspects, CAPS has multiple neurological manifestations. The largest case series to date is presented focusing on the neurological features of this disorder. METHODS: The case histories of a cohort of 38 UK patients with genetically proven CAPS who were treated with interleukin 1ß (IL-1ß) inhibition as part of a national treatment programme and underwent detailed neurological assessment were reviewed. RESULTS: Across the entire disease course neurological manifestations were present in 95% of patients; 84% had some form of headache; 66% sensorineural hearing loss; 60% myalgia; 34% papilloedema and 26% optic atrophy. Patients with the T348M mutation tended to have a more severe neurological phenotype with an earlier age of onset. Four patients had cerebrospinal fluid examination, three of whom had evidence of aseptic meningitis. There was a marked response to IL-1ß inhibition, which has revolutionized management of these patients (29/32 patients with headache responding). CONCLUSION: Neurological symptoms are extremely common in CAPS and these results highlight the importance of increasing awareness amongst neurologists, particularly as highly effective therapies are available.

Cardiac amyloidosis: where are we today?

Systemic amyloidosis is generally considered to be rare, but the heart is frequently involved and is a major determinant of prognosis. New diagnostic imaging methods have recently been developed with the capacity to enhance the accuracy of diagnosis, which will be ever more important with the variety of new treatments on the near horizon. Most cases of cardiac amyloidosis are of either monoclonal immunoglobulin light chain (AL) type, which can occur at any age from young adulthood onwards, or transthyretin (ATTR) type, which can be acquired in elderly individuals or inherited at a younger age. Cardiac involvement is the most serious manifestation of AL amyloidosis, and serum cardiac biomarkers have proved to be of great value in staging disease severity and response to an ever increasing array of chemotherapy agents. Cardiac involvement is the dominant manifestation of nonhereditary ATTR amyloidosis, also known as senile cardiac amyloidosis, the prevalence of which is not known but is probably much greater than currently recognized. A genetic variant in the gene for transthyretin (TTR), which is present in 3-4% of African Americans and probably a similar proportion of black individuals of African descent generally, appears to be associated with increased susceptibility to developing cardiac ATTR amyloidosis in older age. Several novel therapies are in the advanced stages of development for ATTR amyloidosis including TTR protein stabilizers and RNA inhibitors that greatly diminish TTR production. Here, we will review recent developments in the diagnosis and management of cardiac amyloidosis.

Muckle-Wells syndrome in an Indian family associated with NLRP3 mutation.

Muckle-Wells syndrome (MWS) is a rare autosomal dominant disease that belongs to a group of hereditary periodic fever syndromes. It is part of the wider spectrum of the cryopyrin-associated periodic syndrome (CAPS) which has only rarely been described in non-Caucasian individuals. It is characterized by recurrent self-limiting episodes of fever, urticaria, arthralgia, myalgia and conjunctivitis from childhood. Progressive sensorineural hearing loss and amyloidosis are two late complications. MWS is caused by gain of function mutations in the NLRP3 gene, which encodes cryopyrin, a protein involved in regulating the production of proinflammatory cytokines. We report two patients with MWS in an Indian family associated with the p.D303N mutation in the NLRP3 gene. These findings promote awareness of these hereditary periodic fever syndromes as a cause for recurrent fevers from childhood in the Indian population.

The phenotype of TNF receptor-associated autoinflammatory syndrome (TRAPS) at presentation: a series of 158 cases from the Eurofever/EUROTRAPS international registry.

OBJECTIVE: To evaluate the genetic findings, demographic features and clinical presentation of tumour necrosis factor receptor-associated autoinflammatory syndrome (TRAPS) in patients from the Eurofever/EUROTRAPS international registry. METHODS: A web-based registry collected retrospective data on patients with TNFRSF1A sequence variants and inflammatory symptoms. Participating hospitals included paediatric rheumatology centres and adult centres with a specific interest in autoinflammatory diseases. Cases were independently validated by experts in the disease. RESULTS: Complete information on 158 validated patients was available. The most common TNFRSF1A variant was R92Q (34% of cases), followed by T50M (10%). Cysteine residues were disrupted in 27% of cases, accounting for 39% of sequence variants. A family history was present in 19% of patients with R92Q and 64% of those with other variants. The median age at which symptoms began was 4.3 years but 9.1% of patients presented after 30 years of age. Attacks were recurrent in 88% and the commonest features associated with the pathogenic variants were fever (88%), limb pain (85%), abdominal pain (74%), rash (63%) and eye manifestations (45%). Disease associated with R92Q presented slightly later at a median of 5.7 years with significantly less rash or eye signs and more headaches. Children were more likely than adults to present with lymphadenopathy, periorbital oedema and abdominal pains. AA amyloidosis has developed in 16 (10%) patients at a median age of 43 years. CONCLUSIONS: In this, the largest reported case series to date, the genetic heterogeneity of TRAPS is accompanied by a variable phenotype at presentation. Patients had a median 70 symptomatic days a year, with fever, limb and abdominal pain and rash the commonest symptoms. Overall, there is little evidence of a significant effect of age or genotype on disease features at presentation.

Renal transplantation in systemic amyloidosis-importance of amyloid fibril type and precursor protein abundance.

Renal transplantation remains contentious in patients with systemic amyloidosis due to the risk of graft loss from recurrent amyloid and progressive disease. Outcomes were sought among all patients attending the UK National Amyloidosis Centre who received a renal transplant (RTx) between January 1978 and May 2011. A total of 111 RTx were performed in 104 patients. Eighty-nine percent of patients with end-stage renal disease (ESRD) due to hereditary lysozyme and apolipoprotein A-I amyloidosis received a RTx. Outcomes following RTx were generally excellent in these diseases, reflecting their slow natural history; median graft survival was 13.1 years. Only 20% of patients with ESRD due to AA, AL and fibrinogen amyloidosis received a RTx. Median graft survival was 10.3, 5.8 and 7.3 years in these diseases respectively, and outcomes were influenced by fibril precursor protein supply. Patient survival in AL amyloidosis was 8.9 years among those who had achieved at least a partial clonal response compared to 5.2 years among those who had no response (p = 0.02). Post-RTx chemotherapy was administered successfully to four AL patients. RTx outcome is influenced by amyloid type. Suppression of the fibril precursor protein is desirable in the amyloidoses that have a rapid natural history.

Hereditary lysozyme amyloidosis -- phenotypic heterogeneity and the role of solid organ transplantation.

OBJECTIVES: Lysozyme amyloidosis (ALys) is a form of hereditary systemic non-neuropathic amyloidosis, which is inherited in an autosomal dominant fashion. Lysozyme, which is the amyloidogenic precursor protein in ALys, is a ubiquitous bacteriolytic enzyme synthesized by hepatocytes, polymorphs and macrophages. The aim of this study is to describe the phenotype and outcome of patients with ALys including the role of solid organ transplantation. DESIGN: Retrospective evaluation of patients with ALys. SETTING: UK National Amyloidosis Centre. PATIENTS: All 16 patients with ALys followed at the centre. RESULTS: A family history of amyloidosis was present in every affected individual. Although the phenotype was broadly similar amongst those from the same kindred, there were marked phenotypic differences between kindreds who possessed the same amyloidogenic mutation. Symptomatic gastrointestinal (GI) amyloid was prevalent, and macroscopically visible amyloidotic lesions were present in nine of 10 patients who underwent GI endoscopy. All symptomatic ALys individuals had hepatic amyloid. Four patients received orthotopic liver transplants (OLT), three for spontaneous hepatic rupture and one case, who had extensive hepatic amyloid and a strong family history of hepatic rupture, pre-emptively. All of the liver grafts were functioning at censor 1.7, 5.8, 9.0 and 11.0 years after OLT. Five patients had progressive amyloidotic renal dysfunction culminating in end-stage renal failure, three of whom underwent renal transplantation (RTx). There was no evidence of renal allograft dysfunction at censor 6.6, 1.8 and 0.8 years after RTx. CONCLUSIONS: Lysozyme amyloidosis is a disease of the GI tract, liver and kidneys, which has a slow natural history. There was a clear family history in all cases within this cohort, demonstrating a high clinical penetrance in the presence of an amyloidogenic lysozyme mutation. There is currently no amyloid-specific therapy for the condition which is managed symptomatically. OLT and RTx appear to be successful treatments for patients with liver rupture or end-stage renal disease, respectively, with excellent outcomes in terms of medium-term graft function and patient survival.

Two-year results from an open-label, multicentre, phase III study evaluating the safety and efficacy of canakinumab in patients with cryopyrin-associated periodic syndrome across different severity phenotypes.

OBJECTIVE: Longer-term effects of prolonged selective interleukin-1ß blockade with canakinumab were evaluated in the largest cohort of cryopyrin-associated periodic syndrome (CAPS) patients studied to date. METHODS: Adult and paediatric CAPS patients (n=166, including canakinumab-naive and pretreated patients from previous studies) received canakinumab subcutaneously 150 mg or 2 mg/kg (≤40 kg) every 8 weeks for up to 2 years. Response and relapse was assessed using scores for disease activity, skin rash and C-reactive protein (CRP) and/or serum amyloid A (SAA) levels. RESULTS: Complete response was achieved in 85 of 109 canakinumab-naive patients (78%; 79/85 patients within 8 days, and five patients between days 10 and 21). Of 141 patients with an available relapse assessment, 90% did not relapse, their CRP/SAA levels normalised (<10 mg/l) by day 8, and remained in the normal range thereafter. Median treatment duration was 414 days (29-687 days). Upward adjustments of dose or frequency were needed in 24.1% patients; mostly children and those with severe CAPS. Predominant adverse events (AE) were infections (65.7%) of mostly mild-to-moderate severity. Serious AE reported in 18 patients (10.8%) were mainly infections and were responsive to standard treatment. The majority of patients (92%) reported having no injection-site reactions and only 8% patients reported mild-to-moderate reactions. Patients receiving vaccination (15%) showed normal immune response. CONCLUSIONS: Subcutaneous canakinumab 150 mg every 8 weeks was well tolerated and provided substantial disease control in children and adults across all CAPS phenotypes. Higher canakinumab doses in younger patients and more severe CAPS disease were efficacious in achieving complete responses without evidence of increased AE. TRIAL REGISTRATION NUMBER: NCT00685373 (clinicaltrials.gov).

Amyloid deposition is delayed in mice with targeted deletion of the serum amyloid P component gene.

The tissue amyloid deposits that characterize systemic amyloidosis, Alzheimer's disease and the transmissible spongiform encephalopathies always contain serum amyloid P component (SAP) bound to the amyloid fibrils. We have previously proposed that this normal plasma protein may contribute to amyloidogenesis by stabilizing the deposits. Here we show that the induction of reactive amyloidosis is retarded in mice with targeted deletion of the SAP gene. This first demonstration of the participation of SAP in pathogenesis of amyloidosis in vivo confirms that inhibition of SAP binding to amyloid fibrils is an attractive therapeutic target in a range of serious human diseases.

Specific localization and imaging of amyloid deposits in vivo using 123I-labeled serum amyloid P component.

Highly specific, high-resolution scintigraphic images of amyloid-laden organs in mice with experimentally induced amyloid A protein (AA) amyloidosis were obtained after intravenous injection of 123I-labeled serum amyloid P component (SAP). Interestingly, a much higher proportion (up to 40%) of the injected dose of heterologous human SAP localized to amyloid and was retained there than was the case with isologous mouse SAP, indicating that human SAP binds more avidly to mouse AA fibrils than does mouse SAP. Specificity of SAP localization was established by the failure of the related proteins, human C-reactive protein and Limulus C-reactive protein, to deposit significantly in amyloid and by the absence of human SAP deposition in nonamyloidotic organs. However, only partial correlations were observed between the quantity of SAP localized and two independent estimates, histology and RIA for AA of the amount of amyloid in particular organs. It is not clear which of the three methods used reflects better the extent or clinical significance of the amyloid deposits but in vivo localization of radiolabeled SAP, detectable and quantifiable by gamma camera imaging, is apparently extremely sensitive. These findings establish the use of labeled SAP as a noninvasive in vivo diagnostic probe in experimental amyloidosis, potentially capable of revealing the natural history of the condition, and suggest that it may also be applicable generally as a specific targeting agent for diagnostic and even therapeutic purposes in clinical amyloidosis.

Solid organ transplantation in AL amyloidosis.

Vital organ failure remains common in AL amyloidosis. Solid organ transplantation is contentious because of the multisystem nature of this disease and risk of recurrence in the graft. We report outcome among all AL patients evaluated at the UK National Amyloidosis Centre who received solid organ transplants between 1984 and 2009. Renal, cardiac and liver transplants were performed in 22, 14 and 9 patients respectively, representing <2% of all AL patients assessed during the period. One and 5-year patient survival was 95% and 67% among kidney recipients, 86% and 45% among heart recipients and 33% and 22% among liver recipients. No renal graft failed due to recurrent amyloid during median (range) follow up of 4.8 (0.2-13.3) years. Median patient survival was 9.7 years among 8/14 cardiac transplant recipients who underwent subsequent stem cell transplantation (SCT) and 3.4 years in six patients who did not undergo SCT (p = 0.01). Amyloid was widespread in all liver transplant recipients. Solid organ transplantation has rarely been performed in AL amyloidosis, but these findings demonstrate feasibility and support a role in selected patients.

Spinal Stenosis in Familial Transthyretin Amyloidosis.

Here we describe a patient with genetically confirmed ATTR, a family history of the disease and histological confirmation following carpal tunnel release surgery but no other manifestations. The first major neurological or systemic manifestation was cauda equina syndrome with ATTR deposits contributing to lumbar spinal stenosis. Recent gene therapy trials showed improvement in the neuropathy in TTR amyloidosis. This case highlights the need for awareness of the heterogeneous neurological phenotype seen in ATTR to aid earlier diagnosis especially now that disease modifying therapies are available.

Heart transplantation for homozygous familial transthyretin (TTR) V122I cardiac amyloidosis.

Heart failure is the usual cause of death in patients with amyloid cardiomyopathy. The commonest form of hereditary cardiac amyloidosis is associated with the Val122Ile variant of transthyretin (TTR), which is carried by 3-4% of the African American population. Here, we report the outcome of the first cardiac transplantation in a patient with TTR V122I. A 59-year-old Caribbean man presented with biventricular failure. Other than previous bilateral carpel tunnel syndrome, he had been well and had no evidence of extracardiac amyloidosis. An endomyocardial biopsy demonstrated amyloid of TTR type. Sequencing of TTR gene indicated homozygosity for V122I. He underwent cardiac transplantation and 3 years later, remains well with no evidence of allograft or systemic amyloid deposition.

Metabolic and scintigraphic studies of radioiodinated human C-reactive protein in health and disease.

Plasma and whole-body turnover studies of human C-reactive protein (CRP), isolated from a single normal healthy donor and labeled with 125I, were undertaken in 8 healthy control subjects and 35 hospitalized patients including cases of rheumatoid arthritis, systemic lupus erythematosus, infections, and neoplasia. Plasma clearance of 125I-CRP closely approximated to a monoexponential function and was similar in the control and all patient groups. There was no evidence for accelerated clearance or catabolism of CRP in any of the diseases studied. The 19-h half-life was more rapid than that of most human plasma proteins studied previously, and the fractional catabolic rate was independent of the plasma CRP concentration. The synthesis rate of CRP is thus the only significant determinant of its plasma level, confirming the validity of serum CRP measurement as an objective index of disease activity in disorders associated with an acute-phase response. Approximately 90% of injected radioactivity was recovered in the urine after 7 d, and scintigraphic imaging studies with 123I-labeled CRP in 10 patients with different focal pathology showed no significant localization of tracer. The functions of CRP are thus likely to be effected predominantly in the fluid phase rather than by major deposition at sites of tissue damage or inflammation.

Metabolic studies of radioiodinated serum amyloid P component in normal subjects and patients with systemic amyloidosis.

125I-Serum amyloid P component (SAP), injected intravenously into 10 normal subjects, remained predominantly intravascular with mean (SD) T1/2 (half time) in plasma of 24.5 (5.9) h. The fractional catabolic rate of 68 (19)% of the plasma pool per day was more rapid than other reported human plasma proteins. All radioactivity was excreted in the urine by 14 d. In 16 patients with monoclonal gammopathy or chronic inflammatory diseases, but without amyloidosis, 125I-SAP metabolism was normal. However, among 45 patients with biopsy-proven systemic amyloidosis (25, amyloid A type; 20, amyloid L type), 125I-SAP was cleared from the plasma more rapidly, accumulated in the amyloid deposits, and persisted there. The T1/2 in amyloid, measured directly with 131I-SAP, was 24 d. Repeat studies after 6-18 mo were notably consistent in normals but changed significantly in amyloid patients, generally correlating with clinical signs of disease progression. Measurements of 125I-SAP turnover may thus be of value for diagnosis and monitoring of amyloidosis. Analysis of SAP metabolism in amyloidosis suggests that plasma SAP is in dynamic equilibrium with a very large amyloid pool, and in two autopsies the total mass of SAP in the amyloid deposits was 2,100 and 21,000 mg, respectively.

The pentraxins, C-reactive protein and serum amyloid P component, are cleared and catabolized by hepatocytes in vivo.

The cellular sites of clearance and degradation of the pentraxin plasma proteins, C-reactive protein, the classical acute phase reactant, and serum amyloid P component (SAP), a universal constituent of amyloid deposits, were sought using the ligand 125I-tyramine cellobiose (TC) which is substantially retained within the cells in which catabolism takes place. Pentraxins labeled with 125I-TC showed the same in vitro and in vivo ligand binding and the same in vivo plasma t1/2 as the directly iodinated proteins and the native unlabeled pentraxins, indicating that their mode of clearance was likely to be physiological. After intravenous injection into mice and rabbits of human C-reactive protein, human SAP, and mouse SAP, each labeled with 125I-TC, most of the radioactivity remaining in the body at 24 h was located in hepatocytes. None was detected in other liver cells, and only traces were present in other viscera; the rest was in the carcass, representing intact pentraxins in the blood and extravascular compartment, and escaped label which had not yet been excreted. Hepatocytes are thus the single major site of pentraxin clearance and catabolism in vivo. This is consistent with the observation that SAP that has localized to amyloid deposits persists there and is not degraded.

Hereditary hepatic and systemic amyloidosis caused by a new deletion/insertion mutation in the apolipoprotein AI gene.

We report a Spanish family with autosomal-dominant non-neuropathic hereditary amyloidosis with a unique hepatic presentation and death from liver failure, usually by the sixth decade. The disease is caused by a previously unreported deletion/insertion mutation in exon 4 of the apolipoprotein AI (apoAI) gene encoding loss of residues 60-71 of normal mature apoAI and insertion at that position of two new residues, ValThr. Affected individuals are heterozygous for this mutation and have both normal apoAI and variant molecules bearing one extra positive charge, as predicted from the DNA sequence. The amyloid fibrils are composed exclusively of NH2-terminal fragments of the variant, ending mainly at positions corresponding to residues 83 and 92 in the mature wild-type sequence. Amyloid fibrils derived from the other three known amyloidogenic apoAI variants are also composed of similar NH2-terminal fragments. All known amyloidogenic apoAI variants carry one extra positive charge in this region, suggesting that it may be responsible for their enhanced amyloidogenicity. In addition to causing a new phenotype, this is the first deletion mutation to be described in association with hereditary amyloidosis and it significantly extends the value of the apoAI model for investigation of molecular mechanisms of amyloid fibrillogenesis.

A novel amyloidogenic transthyretin variant, Gly53Ala, associated with intermittent headaches and ataxia.

We report a novel transthyretin variant, Gly53Ala, in a 44-year-old British woman who presented with severe episodic headaches, often with focal neurological deficit, before developing progressive ataxia, depression, dementia and eventually peripheral neuropathy. Transthyretin amyloidosis was confirmed on biopsy of the heart muscle. Serum amyloid P component scintigraphy did not show visceral amyloid in extra-cardiac sites, but magnetic resonance imaging indicated diffuse leptomeningeal amyloidosis.