Amyloid Deposits In Patients Research Articles

Digital whole-slide imaging of changes in amyloid after peripheral blood stem cell transplantation in patients with amyloid light-chain amyloidosis.

Peripheral blood stem cell transplantation (PBSCT) has made amyloid light-chain (AL) amyloidosis treatable. After PBSCT, hematological complete remission (HCR) can be achieved, leading to improved renal prognosis. The purpose of this study was to evaluate whether whole slide imaging of biopsy samples shows a post-treatment reduction in amyloid deposits in patients with AL amyloidosis. Patients were divided into three groups: Group A (n = 8), not eligible for PBSCT and treated with other therapies; Group B (n = 11), treated with PBSCT and achieved HCR; and Group C (n = 5), treated with PBSCT but did not achieve HCR. Clinical findings and amyloid deposition in glomeruli, interstitium, and blood vessels were compared before and after treatment using digital whole-slide imaging. Proteinuria and hypoalbuminemia improved more in Group B than in the other groups, and in Group B, amyloid deposition improved more in the glomeruli than in the interstitium and blood vessels. The long-term renal and survival prognosis was better in Group B than in the other groups. PBSCT can be expected to improve long-term clinical and renal histological prognosis in patients with AL amyloidosis who achieve HCR. Amyloid disappearance from renal tissue may take a long time even after clinical HCR.

Amyloid Protein in AL-Amyloidosis. Natural History and Potential for Regression

Amyloid light chain amyloidosis is the most commonly seen form of systemic amyloidosis and is characterized by the accumulation of circulating monoclonal immunoglobulin light chain precursors arising from an abnormal clone of plasma cells. These light chain precursors demonstrate a propensity for misfolding, aggregation and deposition as highly stable fibrillar cross-linked beta sheets in various tissues and organs in a manner characteristic of other forms of systemic amyloidosis. There have been great advances in the treatment of the underlying plasma cell dyscrasia with improved long-term survival but the persistence of extracellular amyloid deposits in the tissues of vital organs, particularly the heart and kidney remains a significant cause of morbidity and mortality even in those patients in whom a hematological complete response has been achieved. This review focuses on the importance of early diagnosis and treatment on limiting the extent of amyloid protein accumulation and organ dysfunction and the current state of knowledge on the potential for resorption and clearance of these amyloid deposits in patients with amyloid light chain amyloidosis. The status of current novel anti-fibrillar agents is reviewed and future strategies for effectively intervening to improve organ function and survival these individuals is discussed.

Quantitative 99mTc-DPD-SPECT/CT assessment of cardiac amyloidosis

IntroductionTransthyretin (ATTR) amyloidosis is responsible for the majority of cardiac amyloidosis (CA) cases and can be reliably diagnosed with bone scintigraphy and the visual Perugini score. We aimed to implement a quantification method of cardiac amyloid deposits in patients with suspected cardiac amyloidosis and to compare performance to visual scoring. Methods and materials136 patients received 99mTc-DPD-bone scintigraphy including SPECT/CT of the thorax in case of suspicion of cardiac amyloidosis. Imaging phantom studies were performed to determine the scaling factor for standardized uptake value (SUV) quantification from SPECT/CT. Myocardial tracer uptake was quantified in a whole heart volume of interest. ResultsForty-five patients were diagnosed with CA. A strong relationship between cardiac SUVmax and Perugini score was found (Spearman r 0.75, p < 0.0001). Additionally, tracer uptake in bone decreased with increasing cardiac SUVmax and Perugini score (p < 0.0001). ROC analysis revealed good performance of the SUVmax for the detection of ATTR-CA with AUC of 0.96 ± 0.02 (p < 0.0001) with sensitivity 98.7% and specificity 87.2%. ConclusionWe demonstrate an accessible and accurate quantitative SPECT approach in CA. Quantitative assessment of the cardiac tracer uptake may improve diagnostic accuracy and risk classification. This method may enable monitoring and assessment of therapy response in patients with ATTR amyloidosis.

Beta 2 microglobulin in kidney failure: A review and an algorithm for renal replacement therapy.

For decades, beta 2 microglobulin (B2M) has been a subject of great interest in nephrology and other fields such as multiple myeloma. B2M, a 99 amino acid protein, is associated with amyloid deposits in patients undergoing renal replacement therapy (RRT). The source of information is published articles on B2M in chronic renal failure since 1960. We have reviewed literature published since 1960 to date, highlighting the milestones of the role of B2M in chronic kidney disease (CKD) and B2M serum values in patients treated by various RRTs. B2M deposits associated with the disease include carpal tunnel syndrome, spondyloarthropathy, and arthritis of large joints such as the shoulders. The role of RRT in the removal of B2M in CKD is discussed. Recent reports include factors affecting the process of fibrillation and deposition of B2M in tissues. A comparative report of various modalities of treatment on the serum levels of B2M is provided. The presence of significant residual urine output in continuous ambulatory peritoneal dialysis patients may explain why peritoneal dialysis is a modality that is associated with the lowest level of serum B2M. Patients treated with hemodiafiltration or hemodialysis (HD) using high flux dialyzers have lower levels of B2M than those treated by HD with low flux dialyzers. Finally, based on the literature review, an algorithm for RRT using B2M level monitoring and other variables is proposed and needs evaluation in a controlled trial.

In Vivo Quantification of Myocardial Amyloid Deposits in Patients with Suspected Transthyretin-Related Amyloidosis (ATTR).

Background: Current diagnosis of Transthyretin-related Amyloidosis (ATTR) using bone scintigraphy is primarily based on visual scoring and semi-quantitative indices. With the introduction of new potential life-prolonging drugs for ATTR, a more precise quantification of myocardial amyloid burden is desirable for improved response prediction and therapy monitoring. Methods: At first, quantification experiments using an anthropomorphic thorax phantom were performed. Second, 32 patients underwent both planar whole body [99mTc]- 3,3-Diphosphono-1,2-Propanodicarboxylic Acid (DPD)-scintigraphy and quantitative Single-Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) of the thorax. SPECT/CT standardized myocardial uptake values SUVpeak and SUVpeak normalized to bone uptake (nSUVpeak) were determined. Results: Phantom measurements showed a strong linear relationship between the activity in the myocardial insert and the measured activity (r = 0.9998, p = 0.01), but the measured activity was systematically underestimated by approximately 30%. Receiver operating characteristics (ROC) analysis revealed a 100% sensitivity and specificity at a cut-off of 3.1 for SUVpeak for the differentiation of both patient groups. Conclusion: SUV quantification of ATTR amyloid burden is feasible using novel SPECT/CT technology. With a SUVpeak cut-off of 3.1, patients with Perugini grade 2 and 3 could be clearly separated from those with Perugini grade 0 and 1. Besides ATTR diagnostics, quantification of amyloid deposits could potentially be used for therapy monitoring and prognostication in patients with cardiac ATTR.

Atrial Fibrillation in the Elderly: The Role of Sub-Clinical Isolated Cardiac Amyloidosis

Amyloid infiltration of the atrium is described in patients with valvular heart disease and is associated with an increased risk for atrial fibrillation(AF) while amyloid deposits in the ventricles is increasingly being diagnosed in patients with HFpEF. The role of amyloid deposits in patients with AF without valvular heart disease, which represents the most common form of AF globally, is undefined. In this study, we sought to assess the prevalence of sub-clinical isolated cardiac amyloidosis (ICA) at autopsy and the odds of AF in these patients. A total of 1083 patients were included in the study and 3.1% of patients were found to have asymptomatic ICA. Patients with ICA were older and had a higher odds of AF independent of age and CHA2DS2VASc score. Amongst patients with AF, those with ICA were more likely to have persistent forms of AF and had a lower sinus rhythm P-wave amplitude. Further studies are required to further define this entity, identify imaging modalities to aid in antemortem diagnosis of ICA and to establish the optimal management strategies in these patients.

Personalizing Amyloidosis Therapy with Real Time PET Imaging of Fibril-Reactive Monoclonal Antibody Cael-101

Background AL amyloidosis is the most common type of systemic amyloidosis in western countries and has a poor prognosis, with a median survival of 12 to 18 months. Despite the improved prognosis gained by eliminating the offending plasma cell clone, mortality remains high due to multi-organ dysfunction caused by persistent, insoluble amyloid fibril deposits. The amyloid fibril-reactive murine monoclonal antibody 11-1F4 was designed to target amyloid deposits by directly binding to a conformational epitope present on human light-chain amyloid fibrils. The murine form of this antibody has demonstrated potential to bind amyloid in mice and humans (Blood. 2010 116: 2241) and to clear insoluble fibrils in mice with induced human AL amyloidomas, demonstrating the feasibility of using immunotherapy to elicit rapid destruction of amyloid fibrils. Of great translational importance, a chimeric form of 11-1F4 was produced (CAEL-101) and recently demonstrated therapeutic potential in an open-label, dose-escalation phase 1a/b study where 67% of patients with cardiac or renal amyloidosis demonstrated organ response. There was a statistically significant change in Global Longitudinal Strain with 9/10 patients showing improvement (p=0.004). Since we have shown that CAEL-101 successfully improved organ function, the overall goal of this work is for the first time to explore the diagnostic potential of CAEL-101 radiolabeled with a positron emitting radioisotope for systemic amyloidosis as well as to explore its use as a companion biomarker to stratify patients for CAEL-101 immunotherapy.Methods We obtained human amyloid extracts from the heart (κ1), liver (κ1), spleen (λ1) and kidney (λ6). Lyophilized human amyloid extracts were suspended in 25ml of sterile PBS and homogenized for 3 minutes and centrifuged at 12,000g for 30 minutes. 100mg of the resulting pellet was resuspended in sterile saline. Balb/c mice were then injected subcutaneously with amyloid extract. For imaging experiments, cGMP grade CAEL-101 was radiolabeled with 124I, a positron emitting radioisotope used for PET imaging, with the standard iodegen reaction. Approximately 5 days after human amyloid extract was implanted to form subcutaneous amyloidomas, animals were injected with 200μCi of [124I]CAEL-101 and imaged 1 and 4 days post injection using an Inveon microPET scanner. SUVmax for amyloidomas and contralateral background were obtained by drawing regions of interest in the PMOD software package and calculating tumor-to-background (T:B) ratios at 1 and 4 days post tracer infusion.Results We found that [124I]CAEL-101 successfully imaged 100% of mice bearing human amyloid extracts (κ1, λ1 and λ6 subtypes derived from heart, liver, spleen, and kidney). Human amyloidomas were visualized at both at 1 and 4 days post tracer infusion, with significantly increasing T:B radio by day 4, as expected when imaging large molecular weight antibodies. T:B ratios ranged from 2.1 to 4.2 at 4 days. Mice implanted with κ subtypes demonstrated significantly better in vivo T:B ratios (4.1 +/- 0.20), compared to λ subtypes (2.8 +/- 0.46), although all amyloidomas exhibited T:B uptake > 2.1, which would be clinically significant.Conclusions We have demonstrated for the first time the potential of using radiolabeled CAEL-101 as a companion diagnostic to image real-time targeting of human amyloidosis in vivo. This is highly translatable due to the fact that CAEL-101 has shown great promise in early stage clinical trials to clear insoluble amyloid plaques. Importantly, we successfully used PET imaging to visualize cardiac derived amyloid fibrils from AL amyloidosis patients. Therefore, we anticipate that dedicated gated cardiac PET/CT imaging of radiolabeled CAEL-101 will be successful at visualizing cardiac amyloid deposits in patients, especially with the rich blood flow in cardiac tissue and newer generation highly sensitive, high resolution digital PET scanners, in contrast to the non-cardiac optimized whole body scans used in prior studies with antibody-based PET. Given that we were able to image 100% of implanted human amyloidomas derived from heart, spleen, liver and kidney consisting of both κ and λ subtypes, we envision using CAEL-101 PET imaging to (1) diagnose systemic amyloidosis, (2) stratify patients for CAEL-101 immunotherapy, and (3) quantify peripheral organ amyloid fibril deposition pre and post anti-amyloid therapy. [Display omitted] DisclosuresSolomon:Caelum Biosciences: Consultancy, Equity Ownership. Lentzsch:Bayer: Consultancy; BMS: Consultancy; Janssen: Consultancy; Caelum Biosciences: Consultancy, Other: Dr. Lentzsch recused herself as an investigator from the Phase 1a/b trial testing CAEL-101 in 11/2017., Patents & Royalties: Shareholder for Caelum Biosiences. Mintz:Caelum Biosciences: Research Funding.

Tenosynovial and Cardiac Amyloidosis in Patients Undergoing Carpal Tunnel Release

BackgroundPatients with cardiac amyloidosis often have carpal tunnel syndrome that precedes cardiac manifestations by several years. However, the prevalence of cardiac involvement at the time of carpal tunnel surgery has not been established. ObjectivesThe authors sought to identify the prevalence and type of amyloid deposits in patients undergoing carpal tunnel surgery and evaluate for cardiac involvement. The authors also sought to determine if patients with soft tissue transthyretin (TTR) amyloid had abnormal TTR tetramer kinetic stability. MethodsThis was a prospective, cross-sectional, multidisciplinary study of consecutive men age ≥50 years and women ≥60 years undergoing carpal tunnel release surgery. Biopsy specimens of tenosynovial tissue were obtained and stained with Congo red; those with confirmed amyloid deposits were typed with mass spectrometry and further evaluated for cardiac involvement with biomarkers, electrocardiography, echocardiography with longitudinal strain, and technetium pyrophosphate scintigraphy. Additionally, serum TTR concentration and tetramer kinetic stability were examined. ResultsOf 98 patients enrolled (median age 68 years, 51% male), 10 (10.2%) had a positive biopsy for amyloid (7 ATTR, 2 light chain [AL], 1 untyped). Two patients were diagnosed with hereditary ATTR (Leu58His and Ala81Thr), 2 were found to have cardiac involvement (1 AL, 1 ATTR wild-type), and 3 were initiated on therapy. In those patients who had biopsy-diagnosed ATTR, there was no difference in plasma TTR concentration or tetramer kinetic stability. ConclusionsIn a cohort of patients undergoing carpal tunnel release surgery, Congo red staining of tenosynovial tissue detected amyloid deposits in 10.2% of patients. Concomitant cardiac evaluation identified patients with involvement of the myocardium, allowing for implementation of disease-modifying therapy. (Carpal Tunnel Syndrome and Amyloid Cardiomyopathy; NCT02792790)

BRICHOS domain of Bri2 inhibits islet amyloid polypeptide (IAPP) fibril formation and toxicity in human beta cells

Aggregation of islet amyloid polypeptide (IAPP) into amyloid fibrils in islets of Langerhans is associated with type 2 diabetes, and formation of toxic IAPP species is believed to contribute to the loss of insulin-producing beta cells. The BRICHOS domain of integral membrane protein 2B (Bri2), a transmembrane protein expressed in several peripheral tissues and in the brain, has recently been shown to prevent fibril formation and toxicity of Aβ42, an amyloid-forming peptide in Alzheimer disease. In this study, we demonstrate expression of Bri2 in human islets and in the human beta-cell line EndoC-βH1. Bri2 colocalizes with IAPP intracellularly and is present in amyloid deposits in patients with type 2 diabetes. The BRICHOS domain of Bri2 effectively inhibits fibril formation in vitro and instead redirects IAPP into formation of amorphous aggregates. Reduction of endogenous Bri2 in EndoC-βH1 cells with siRNA increases sensitivity to metabolic stress leading to cell death while a concomitant overexpression of Bri2 BRICHOS is protective. Also, coexpression of IAPP and Bri2 BRICHOS in lateral ventral neurons of Drosophila melanogaster results in an increased cell survival. IAPP is considered to be the most amyloidogenic peptide known, and described findings identify Bri2, or in particular its BRICHOS domain, as an important potential endogenous inhibitor of IAPP aggregation and toxicity, with the potential to be a possible target for the treatment of type 2 diabetes.

Repeat doses of antibody to serum amyloid P component clear amyloid deposits in patients with systemic amyloidosis.

Systemic amyloidosis is a fatal disorder caused by pathological extracellular deposits of amyloid fibrils that are always coated with the normal plasma protein, serum amyloid P component (SAP). The small-molecule drug, miridesap, [(R)-1-[6-[(R)-2-carboxy-pyrrolidin-1-yl]-6-oxo-hexanoyl]pyrrolidine-2-carboxylic acid (CPHPC)] depletes circulating SAP but leaves some SAP in amyloid deposits. This residual SAP is a specific target for dezamizumab, a fully humanized monoclonal IgG1 anti-SAP antibody that triggers immunotherapeutic clearance of amyloid. We report the safety, pharmacokinetics, and dose-response effects of up to three cycles of miridesap followed by dezamizumab in 23 adult subjects with systemic amyloidosis (ClinicalTrials.gov identifier: NCT01777243). Amyloid load was measured scintigraphically by amyloid-specific radioligand binding of 123I-labeled SAP or of 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid. Organ extracellular volume was measured by equilibrium magnetic resonance imaging and liver stiffness by transient elastography. The treatment was well tolerated with the main adverse event being self-limiting early onset rashes after higher antibody doses related to whole body amyloid load. Progressive dose-related clearance of hepatic amyloid was associated with improved liver function tests. 123I-SAP scintigraphy confirmed amyloid removal from the spleen and kidneys. No adverse cardiac events attributable to the intervention occurred in the six subjects with cardiac amyloidosis. Amyloid load reduction by miridesap treatment followed by dezamizumab has the potential to improve management and outcome in systemic amyloidosis.

Clinicopathological and biochemical findings of thyroid amyloid in hereditary transthyretin amyloidosis with and without liver transplantation

Hereditary transthyretin (TTR) amyloidosis is a fatal disease causing systemic organ dysfunctions. Histopathological studies revealed that thyroid glands are major target tissues. However, details about thyroid functions remain to be fully elucidated in this disease. For patient treatment, liver transplantation (LT) reportedly prolongs patient survival, but thyroid gland function after LT still remains poorly understood. In this study, we investigated the thyroid functions in 101 patients with hereditary TTR amyloidosis and the effects of LT on thyroid functions in those patients. In addition, we investigated histopathological and biochemical findings of thyroid specimens obtained at autopsy. Disease duration and age at examination inversely correlated with serum levels of free triiodothyronine (fT3) in hereditary TTR amyloidosis. On the contrary, in patients who underwent transplantation, time from disease onset to transplantation and age at transplantation clearly correlated with serum fT3and thyroid stimulating hormone (TSH) levels. In autopsy studies, amounts of thyroid amyloid deposits in patients with transplantation were significantly lower than those in patients without transplantation. Mass spectrometric analyzes also revealed that proportions of wild-type (WT) TTR in thyroid amyloid deposits in patients with hereditary TTR amyloidosis who underwent transplantations were higher than those in patients without transplantation. Thyroid hormone functions may diminish according to the disease progression. LT could prevent thyroid dysfunction in hereditary TTR amyloidosis.

Causative factors for formation of toxic islet amyloid polypeptide oligomer in type 2 diabetes mellitus.

Human islet amyloid polypeptide (h-IAPP) is a peptide hormone that is synthesized and cosecreted with insulin from insulin-secreting pancreatic β-cells. Recently, h-IAPP was proposed to be the main component responsible for the cytotoxic pancreatic amyloid deposits in patients with type 2 diabetes mellitus (T2DM). Since the causative factors of IAPP (or amylin) oligomer aggregation are not fully understood, this review will discuss the various forms of h-IAPP aggregation. Not all forms of IAPP aggregates trigger the destruction of β-cell function and loss of β-cell mass; however, toxic oligomers do trigger these events. Once these toxic oligomers form under abnormal metabolic conditions in T2DM, they can lead to cell disruption by inducing cell membrane destabilization. In this review, the various factors that have been shown to induce toxic IAPP oligomer formation will be presented, as well as the potential mechanism of oligomer and fibril formation from pro-IAPPs. Initially, pro-IAPPs undergo enzymatic reactions to produce the IAPP monomers, which can then develop into oligomers and fibrils. By this mechanism, toxic oligomers could be generated by diverse pathway components. Thus, the interconnections between factors that influence amyloid aggregation (eg, absence of PC2 enzyme, deamidation, reduction of disulfide bonds, environmental factors in the cell, genetic mutations, copper metal ions, and heparin) will be presented. Hence, this review will aid in understanding the fundamental causative factors contributing to IAPP oligomer formation and support studies for investigating novel T2DM therapeutic approaches, such as the development of inhibitory agents for preventing oligomerization at the early stages of diabetic pathology.

Pentraxins interact with misfolded proteins and inhibit aberrant innate immune activation (INC1P.361)

Abstract Amyloid deposition is linked to different diseases, including Alzheimer’s disease and systemic amyloidosis. How misfolded proteins, including amyloid and its in-process products, are controlled by the host remains obscure. Pentraxins are multimeric pattern recognition proteins that bind to diverse ligands and promote the clearance of microbes. Serum amyloid P-component (SAP), a short chain pentraxin, associates with amyloid deposits in patients. We hypothesize that pentraxins may interact with different forms of misfolded proteins and modulate their biological impact. We found that human SAP readily bound to all types of amyloids, including protein-only, DNA-containing or heparin-containing fibrils. This interaction depended on the presence of calcium. Interestingly, both SAP and C-reactive protein (CRP), another pentraxin, bound to soluble amyloid precursor (AP) protein in the absence of divalent cations. Furthermore, SAP decamer recognized AP whereas aggregated SAP preferentially associated with amyloid. The misfolded structure in AP was necessary for binding to SAP and CRP. DNA-containing amyloid (A-DNA) triggers type I interferon (IFN-I) production by plasmacytoid dendritic cells (pDCs) and promotes lupus-like disease. Binding of SAP to A-DNA inhibited the production of IFN-I by human pDCs. Altogether, our data suggest that pentraxins differentially interact with various forms of misfolded proteins and modulate their ability to stimulate aberrant innate immune activation.

Appropriate use criteria for amyloid PET imaging cannot replace guidelines: On behalf of the European Association of Nuclear Medicine

In the past 10 years, the development and evaluation of PET tracers for imaging fibrillar amyloid in the human brain in patients with Alzheimer’s disease (AD) has been very successful. Brain β-amyloid plaque load is one of the “neuropathological hallmarks” of AD and has been implicated in the pathogenesis and therapy of AD. The recent approval of [F]florbetapir by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) in April and January 2013, respectively, for PET imaging of cerebral amyloid underlines the achievement of an important goal of molecular imaging, and emphasizes the potential role of this tool in the early diagnosis and management of patients with dementia. There are, however, some cautions concerning the use of brain amyloid radiotracers in clinical practice that have to be addressed. Therefore, the Alzheimer’s Association and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) convened the Amyloid Imaging Taskforce (AIT). The AIT recently published their guidance report in which they describe “specific use criteria” which underlines their vision of the clinical utility of amyloid PET [1]. Since we believe that amyloid imaging will be an important new tool for routine clinical studies in the near future, we resolved to provide a brief description and evaluation of this new technique and the most important topics described in the report. In addition we provide some comments on the report [1]. A hallmark study by Klunk and coworkers, published in 2004, was the first study showing that the [C]-labelled tracer termed Pittsburgh Compound-B (PiB) is able to detect amyloid deposits in patients suffering from AD [2]. Subsequently many studies have replicated this finding [3–7]. Also, a substantial number of papers on [C]PiB PET have been published in the European Journal of Nuclear Medicine and

In Vivo Visualization of Amyloid Deposits in the Heart with 11C-PIB and PET

Cardiac amyloidosis is a differential diagnosis in heart failure and is associated with high mortality. There is currently no noninvasive imaging test available for specific diagnosis. N-[methyl-(11)C]2-(4'-methylamino-phenyl)-6-hydroxybenzothiazole ((11)C-PIB) PET is used in the evaluation of brain amyloidosis. We evaluated the potential use of (11)C-PIB PET in systemic amyloidosis affecting the heart. Patients (n = 10) diagnosed with systemic amyloidosis-including heart involvement of either monoclonal immunoglobulin light-chain (AL) or transthyretin (ATTR) type-and healthy volunteers (n = 5) were investigated with PET/CT using (11)C-PIB to study cardiac amyloid deposits and with (11)C-acetate to measure myocardial blood flow to study the impact of global and regional perfusion on PIB retention. Myocardial (11)C-PIB uptake was visually evident in all patients 15-25 min after injection and was not seen in any volunteer. A significant difference in (11)C-PIB retention in the heart between patients and healthy controls was found. The data indicate that myocardial amyloid deposits in patients diagnosed with systemic amyloidosis could be visualized with (11)C-PIB. No correlation between (11)C-PIB retention index and myocardial blood flow as measured with (11)C-acetate was found on the global level, whereas a positive correlation on the segmental level was seen in a single patient. (11)C-PIB and PET could be a method to study systemic amyloidosis of type AL and ATTR affecting the heart and should be investigated further both as a diagnostic tool and as a noninvasive method for treatment follow-up.

External beam radiation therapy is safe and effective in treating primary pulmonary amyloidosis

The aim of the prospective study was to explore the safety and effectiveness of external beam radiation therapy (EBRT) in three patients with biopsy proven primary pulmonary amyloidosis, including two tracheobronchial amyloidosis patients and one primary parenchymal amyloidosis patient. All three patients were treated to 24 Gy in 12 fractions utilizing CT simulation and 3-D planning. All three patients had significant improvement in clinical symptoms, radiological imaging as well as pulmonary function tests. The improvement in the clinical symptoms was evident in 2 days. Toxicities related to EBRT were not observed during the follow-up range from 42 to 54 months. EBRT to 24 Gy was safe and effective in the three patients with primary pulmonary amyloidosis, and resulted in rapid relief of pulmonary symptoms.

Experimentally Derived Structural Constraints for Amyloid Fibrils of Wild-Type Transthyretin

Transthyretin (TTR) is a largely β-sheet serum protein responsible for transporting thyroxine and vitamin A. TTR is found in amyloid deposits of patients with senile systemic amyloidosis. TTR mutants lead to familial amyloidotic polyneuropathy and familial amyloid cardiomyopathy, with an earlier age of onset. Studies of amyloid fibrils of familial amyloidotic polyneuropathy mutant TTR suggest a structure similar to the native state with only a simple opening of a β-strand-loop-strand region exposing the two main β-sheets of the protein for fibril elongation. However, we find that the wild-type TTR sequence forms amyloid fibrils that are considerably different from the previously suggested amyloid structure. Using protease digestion with mass spectrometry, we observe the amyloid core to be primarily composed of the C-terminal region, starting around residue 50. Solid-state NMR measurements prove that TTR differs from other pathological amyloids in not having an in-register parallel β-sheet architecture. We also find that the TTR amyloid is incapable of binding thyroxine as monitored by either isothermal calorimetry or 1,8-anilinonaphthalene sulfonate competition. Taken together, our experiments are consistent with a significantly different configuration of the β-sheets compared to the previously suggested structure.

Radioimmunodetection of amyloid deposits in patients with AL amyloidosis

AbstractCare of patients with AL amyloidosis currently is limited by the lack of objective means to document disease extent, as well as therapeutic options that expedite removal of pathologic deposits. To address these issues, we have initiated a Phase I Exploratory IND study to determine the biodistribution of the fibril-reactive, amyloidolytic murine IgG1 mAb 11-1F4 labeled with I-124. Patients were infused with less than 1 mg (∼ 74 MBq) of GMP-grade antibody and imaged by PET/CT scan 48 and 120 hours later. Among 9 of 18 subjects, there was striking uptake of the reagent in liver, lymph nodes, bone marrow, intestine, or, unexpectedly, spleen (but not kidneys or heart). Generally, positive or negative results correlated with those obtained immunohistochemically using diagnostic tissue biopsy specimens. Based on these findings, we posit that 124I-mAb m11-1F4 can be used to identify AL candidates for passive immunotherapy using the chimeric form of the antibody. This trial was registered at www.clinicaltrials.gov as NCT00807872.

Keratoconus Associated With Corneal Stromal Amyloid Deposition Containing TGFBIp

To report the identification and characterization of stromal amyloid deposits in patients with keratoconus. The excised corneal buttons from 2 patients diagnosed clinically with keratoconus underwent histochemical analysis with Masson trichrome, Congo red, Alcian blue, and periodic acid-Schiff stains, and immunohistochemical analysis for the transforming growth factor beta-induced gene (TGFBI) protein product (TGFBIp), prealbumin, lysozyme, and kappa and lambda light chain expression. After the collection of DNA from both patients, exons 4, 11, 12, 13 and 14 of TGFBI were amplified and sequenced to search for mutations previously associated with dystrophic corneal stromal amyloid deposition. Light microscopic examination of the corneal buttons revealed stromal thinning, epithelial basement membrane abnormalities, and focal disruption of Bowman layer. Multiple stromal deposits were identified that stained red with Masson trichrome, pink with periodic acid-Schiff, and red with Congo red; the Congo red-stained deposits demonstrated birefringence and dichroism with crossed polarizing lenses. Immunohistochemical staining demonstrated reactivity of the stromal deposits with antibodies to TGFBIp but no reactivity with antibodies against prealbumin, lysozyme, or kappa and lambda light chains. Screening of TGFBI exons 4, 11, 12, 13, and 14 revealed 2 previously identified single nucleotide polymorphisms present in the heterozygous state in both individuals but no other coding region variants. Two cases of keratoconus with clinically unsuspected, presumed secondary stromal amyloid deposition are described. Although TGFBIp is identified in the stromal deposits, no previously reported amyloidogenic mutations are identified in TGFBI in either affected individual, indicating a previously undescribed mechanism of stromal amyloid deposition.

β2-microglobulin: from physiology to amyloidosis

β2-microglobulin (β2m) is capable of forming amyloid in osteoarticular structures in kidney failure patients that undergo chronic hemodialysis treatment. Although sophisticated analytical methods have yielded comprehensive data about the conformation of the native protein both as a monomer and as the light chain of the type I major histocompatibility complex, the cause and mechanisms leading to the transformation of β2m into amyloid deposits in patients with dialysis-related amyloidosis are unsettled. The impact on conformational stability of various truncations, cleavages, amino acid substitutions, and divalent cations, especially Cu2+, however, are highly relevant for understanding β2m unfolding pathways leading to amyloid formation. This review describes the current knowledge about such conformationally destabilizing and amyloidogenic factors and links these to the structure and function of β2m in normal physiology and pathology. Tables listing modifications of β2m found in amyloid from patients and a systematic overview of laboratory conditions conducive to β2m-fibrillogenesis are also included.