Classification of amyloidosis: misdiagnosing by way of incomplete immunohistochemistry and how to prevent it

Effect of dynamic exclusion and the use of FAIMS, DIA and MALDI-mass spectrometry imaging with ion mobility on amyloid protein identification

Amyloidosis is a disease characterized by local and systemic extracellular deposition of amyloid protein fibrils where its excessive accumulation in tissues and resistance to degradation can lead to organ failure. Diagnosis is challenging because of approximately 36 different amyloid protein subtypes. Imaging methods like immunohistochemistry and the use of Congo red staining of amyloid proteins for laser capture microdissection combined with liquid chromatography tandem mass spectrometry (LMD/LC-MS/MS) are two diagnostic methods currently used depending on the expertise of the pathology laboratory. Here, we demonstrate a streamlined in situ amyloid peptide spatial mapping by Matrix Assisted Laser Desorption Ionization-Mass Spectrometry Imaging (MALDI-MSI) combined with Trapped Ion Mobility Spectrometry for potential transthyretin (ATTR) amyloidosis subtyping. While we utilized the standard LMD/LC-MS/MS workflow for amyloid subtyping of 31 specimens from different organs, we also evaluated the potential introduction in the MS workflow variations in data acquisition parameters like dynamic exclusion, or testing Data Dependent Acquisition combined with High-Field Asymmetric Waveform Ion Mobility Spectrometry (DDA FAIMS) versus Data Independent Acquisition (DIA) for enhanced amyloid protein identification at shorter acquisition times. We also demonstrate the use of Mascot's Error Tolerant Search and PEAKS de novo sequencing for the sequence variant analysis of amyloidosis specimens.

2024 Australia-New Zealand Expert Consensus Statement on Cardiac Amyloidosis

Over the past 5 years, early diagnosis of and new treatments for cardiac amyloidosis (CA) have emerged that hold promise for early intervention. These include non-invasive diagnostic tests and disease modifying therapies. Recently, CA has been one of the first types of cardiomyopathy to be treated with gene editing techniques. Although these therapies are not yet widely available to patients in Australia and New Zealand, this may change in the near future. Given the rapid pace with which this field is evolving, it is important to view these advances within the Australian and New Zealand context. This Consensus Statement aims to update the Australian and New Zealand general physician and cardiologist with regards to the diagnosis, investigations, and management of CA.

Amino acid sequence homology of monoclonal serum free light chain dimers and tissue deposited light chains in AL amyloidosis: a pilot study

OBJECTIVES

Diagnosis of light chain amyloidosis (AL) requires demonstration of amyloid deposits in a tissue biopsy followed by appropriate typing. Previous studies demonstrated increased dimerization of monoclonal serum free light chains (FLCs) as a pathological feature of AL. To further examine the pathogenicity of FLC, we aimed at testing amino acid sequence homology between circulating and deposited light chains (LCs).

METHODS

Matched tissue biopsy and serum of 10 AL patients were subjected to tissue proteomic amyloid typing and nephelometric FLC assay, respectively. Serum FLC monomers (M) and dimers (D) were analyzed by Western blotting (WB) and mass spectrometry (MS).

RESULTS

WB of serum FLCs showed predominance of either κ or λ type, in agreement with the nephelometric assay data. Abnormal FLC M-D patterns typical of AL amyloidosis were demonstrated in 8 AL-λ patients and in one of two AL-κ patients: increased levels of monoclonal FLC dimers, high D/M ratio values of involved FLCs, and high ratios of involved to uninvolved dimeric FLCs. MS of serum FLC dimers showed predominant constant domain sequences, in concordance with the tissue proteomic amyloid typing. Most importantly, variable domain sequence homology between circulating and deposited LC species was demonstrated, mainly in AL-λ cases.

CONCLUSIONS

This is the first study to demonstrate homology between circulating FLCs and tissue-deposited LCs in AL-λ amyloidosis. The applied methodology can facilitate studying the pathogenicity of circulating FLC dimers in AL amyloidosis. The study also highlights the potential of FLC monomer and dimer analysis as a non-invasive screening tool for this disease.

Diagnostic Challenges and Solutions in Systemic Amyloidosis

Amyloidosis refers to a clinically heterogeneous group of disorders characterized by the extracellular deposition of amyloid proteins in various tissues of the body. To date, 42 different amyloid proteins that originate from normal precursor proteins and are associated with distinct clinical forms of amyloidosis have been described. Identification of the amyloid type is essential in clinical practice, since prognosis and treatment regimens both vary according to the particular amyloid disease. However, typing of amyloid protein is often challenging, especially in the two most common forms of amyloidosis, i.e., the immunoglobulin light chain amyloidosis and transthyretin amyloidosis. Diagnostic methodology is based on tissue examinations as well as on noninvasive techniques including serological and imaging studies. Tissue examinations vary depending on the tissue preparation mode, i.e., whether it is fresh-frozen or fixed, and they can be carried out by ample methodologies including immunohistochemistry, immunofluorescence, immunoelectron microscopy, Western blotting, and proteomic analysis. In this review, we summarize current methodological approaches used for the diagnosis of amyloidosis and discusses their utility, advantages, and limitations. Special attention is paid to the simplicity of the procedures and their availability in clinical diagnostic laboratories. Finally, we describe new methods recently developed by our team to overcome limitations existing in the standard assays used in common practice.

Systemic amyloidosis journey from diagnosis to outcomes: a twelve-year real-world experience of a single center in a middle-income country

BACKGROUND

Systemic amyloidosis is caused by the deposition of misfolded protein aggregates in tissues, leading to progressive organ dysfunction and death. Epidemiological studies originate predominantly from high-income countries, with few data from Latin America. Due to the non-specific clinical manifestations, diagnosing amyloidosis is often challenging and patients experience a long journey and delay in diagnosis. This study aimed to assess clinical and laboratory characteristics, the diagnostic journey, and outcomes of patients with biopsy-proven systemic amyloidosis diagnosed between 2009 and 2020 at a university referral center in a middle-income Latin American country. Patients´ medical records were retrospectively reviewed.

RESULTS

One hundred and forty-three patients were included. The median age at diagnosis was 60 years and 54% were male. Until the diagnosis, most of the patients (52%) were seen by at least 3 specialists, the main ones being: general practitioners (57%), nephrologists (45%), and cardiologists (38%). The most common manifestations were renal (54%) and cardiac (41%) disorders, and cachexia was seen in 36% of patients. In 72% of the cases, ≥ 2 biopsies were required until the final diagnosis. The median time from symptoms onset to diagnosis was 10.9 months, and most patients (75%) had ≥ 2 organs involved. The following subtypes were identified: AL (68%), ATTR (13%), AA (8%), AFib (4%), and inconclusive (7%). Median OS was 74.3 months in the non-AL subgroup and 18.5 months in AL. Among AL patients, those with advanced cardiac stage had the worst outcome [median OS 8.6 months versus 52.3 for stage III versus I-II, respectively (p < 0.001)]. AL subtype, cardiac involvement, and ECOG ≥ 2 were identified as independent risk factors for reduced survival.

CONCLUSIONS

Systemic amyloidosis is still an underdiagnosed condition and the delay in its recognition leads to poor outcomes. Medical education, better diagnostic tools, improvement in access to therapies, and establishment of referral centers may improve patient outcomes in middle-income countries.

Amyloidosis: What does pathology offer? The evolving field of tissue biopsy

Since the mid-nineteenth century pathology has followed the convoluted story of amyloidosis, recognized its morphology in tissues and made identification possible using specific staining. Since then, pathology studies have made a significant contribution and advanced knowledge of the disease, so providing valuable information on the pathophysiology of amyloid aggregation and opening the way to clinical studies and non-invasive diagnostic techniques. As amyloidosis is a heterogeneous disease with various organ and tissue deposition patterns, histology evaluation, far from offering a simple yes/no indication of amyloid presence, can provide a wide spectrum of qualitative and quantitative information related to and changing with the etiology of the disease, the comorbidities and the clinical characteristics of patients. With the exception of cardiac transthyretin related amyloidosis cases, which today can be diagnosed using non-biopsy algorithms when stringent clinical criteria are met, tissue biopsy is still an essential tool for a definitive diagnosis in doubtful cases and also to define etiology by typing amyloid fibrils. This review describes the histologic approach to amyloidosis today and the current role of tissue screening biopsy or targeted organ biopsy protocols in the light of present diagnostic algorithms and various clinical situations, with particular focus on endomyocardial and renal biopsies. Special attention is given to techniques for typing amyloid fibril proteins, necessary for the new therapies available today for cardiac transthyretin related amyloidosis and to avoid patients receiving inappropriate chemotherapy in presence of plasma cell dyscrasia unrelated to amyloidosis. As the disease is still burdened with high mortality, the role of tissue biopsy in early diagnosis to assure prompt treatment is also mentioned.

Cardiac amyloidosis in non-transplant cardiac surgery

Cardiac amyloidosis is a rare infiltrative cardiomyopathy that portends a poor prognosis. There is a growing recognition of co-existent aortic valve stenosis and transthyretin cardiac amyloidosis, with some studies suggesting that dual pathology may be associated increased risk of complication and mortality during surgical intervention. This review aims to evaluate the available literature on non-transplant cardiac surgical interventions in patients with cardiac amyloidosis, with particular focus on diagnosis, high surgical risk and areas of uncertainty that require further research.

Immunoglobulin light chain amyloidosis: 2020 update on diagnosis, prognosis, and treatment

DISEASE OVERVIEW

Immunoglobulin light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of immunoglobulin light or heavy chain are deposited in tissues. Clinical features depend on organs involved but can include heart failure with preserved ejection fraction, nephrotic syndrome, hepatic dysfunction, peripheral/autonomic neuropathy, and "atypical smoldering multiple myeloma or monoclonal gammopathy undetermined significance (MGUS)."

DIAGNOSIS

Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for diagnosis. Invasive organ biopsy is not required in 85% of patients. Verification that amyloid is composed of immunoglobulin light chains is mandatory. The gold standard is laser capture mass spectroscopy.

PROGNOSIS

N-terminal pro-brain natriuretic peptide (NT-proBNP), serum troponin T, and difference between involved and uninvolved immunoglobulin free light chain (FLC) values are used to classify patients into four groups of similar size; median survivals are 94.1, 40.3, 14.0, and 5.8 months.

THERAPY

All patients with a systemic amyloid syndrome require therapy to prevent deposition of amyloid in other organs and prevent progressive organ failure. Stem cell transplant (SCT) is preferred, but only 20% of patients are eligible. Requirements for safe SCT include systolic blood pressure >90 mmHg, troponin T < 0.06 ng/mL and serum creatinine ≤1.7 mg/dL. Nontransplant candidates can be offered cyclophosphamide-bortezomib-dexamethasone or daratumumab-containing regimens as it appears to be highly active in AL amyloidosis.

FUTURE CHALLENGES

Delayed diagnosis remains a major obstacle to initiating effective therapy prior to the development of end-stage organ failure.

Typing of hereditary renal amyloidosis presenting with isolated glomerular amyloid deposition

Background

The commonly used methods for amyloid typing include immunofluorescence or immunohistochemistry (IHC), which sometimes may come with diagnostic pitfalls. Mass spectrometry (MS)-based proteomics has been recognized as a reliable technique in amyloid typing.

Case presentation

We reported two middle-aged patients who presented with proteinuria, hypertension and normal renal function, and both had a family history of renal diseases. The renal biopsies of both patients revealed renal amyloidosis with the similar pattern by massive exclusively glomerular amyloid deposition. The IHC was performed by using a panel of antibodies against the common types of systemic amyloidosis, and demonstrated co-deposition of fibrinogen Aα chain and apolipoprotein A-I in the glomerular amyloid deposits of each patient. Then the MS on amyloid deposits captured by laser microdissection (LMD/MS) and genetic study of gene mutations were investigated. The large spectra corresponding to ApoA-I in case 1, and fibrinogen Aα chain in case 2 were identified by LMD/MS respectively. Further analysis of genomic DNA mutations demonstrated a heterozygous mutation of p. Trp74Arg in ApoA-I in case 1, and a heterozygous mutation of p. Arg547GlyfsTer21 in fibrinogen Aα chain in case 2.

Conclusions

The current study revealed that IHC was not reliable for accurate amyloid typing, and that MS-based proteomics and genetic analysis were essential for typing of hereditary amyloidosis.

Advances in the treatment of hereditary transthyretin amyloidosis: A review

INTRODUCTION

Amyloid transthyretin amyloidosis (ATTR) is a progressive and often fatal disease caused by the buildup of mutated (hereditary ATTR [hATTR]; also known as ATTR variant [ATTRv]) or normal transthyretin (wild-type ATTR) throughout the body. Two new therapies-inotersen, an antisense oligonucleotide therapy, and patisiran, an RNA interference therapy-received marketing authorization and represent a significant advance in the treatment of amyloidosis. Herein, we describe the clinical presentation of ATTR, commonly used procedures in its diagnosis, and current treatment landscape for ATTR, with a focus on hATTR.

METHODS

A PubMed search from 2008 to September 2018 was conducted to review the literature on ATTR.

RESULTS

Until recently, there have been few treatment options for polyneuropathy of hATTR. Inotersen and patisiran substantially reduce the amyloidogenic precursor protein transthyretin and have demonstrated efficacy in patients with early- and late-stage disease and in slowing or improving neuropathy progression. In contrast, established therapies, such as liver transplantation, typically reserved for patients with early-stage disease, and tafamidis, indicated for the treatment of early-stage disease in Europe, or diflunisal, a nonsteroidal anti-inflammatory drug that is used off-label, are associated with side effects and/or unclear efficacy in certain patient populations. Thus, inotersen and patisiran are positioned to be the preferred therapeutic modalities.

CONCLUSIONS

Important differences between inotersen and patisiran, including formulation, dosing, requirements for premedications, and safety monitoring, require an understanding and knowledge of each treatment for informed decision making.

Immunoglobulin light chain amyloidosis: 2018 Update on diagnosis, prognosis, and treatment

DISEASE OVERVIEW

Immunoglobulin light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of immunoglobulin light or heavy chain are deposited in tissues. Clinical features depend on organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic dysfunction, peripheral/autonomic neuropathy, and "atypical multiple myeloma."

DIAGNOSIS

Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for diagnosis. Invasive organ biopsy is not required because amyloid deposits can be found in bone marrow, salivary gland, or subcutaneous fat aspirate in 85% of patients. Verification that amyloid is composed of immunoglobulin light chains is mandatory. The gold standard is laser capture mass spectroscopy.

PROGNOSIS

N-terminal pro-brain natriuretic peptide (NT-proBNP), serum troponin T, and difference between involved and uninvolved immunoglobulin free light chain values are used to classify patients into four groups of similar size; median survivals are 94.1, 40.3, 14.0, and 5.8 months.

THERAPY

All patients with a systemic amyloid syndrome require therapy to prevent deposition of amyloid in other organs and prevent progressive organ failure. Stem cell transplant (SCT) is preferred, but only 20% of patients are eligible. Requirements for safe SCT include systolic blood pressure >90 mm Hg, troponin T < 0.06 ng/mL, age < 70 years, and serum creatinine ≤1.7 mg/dL. Nontransplant candidates can be offered melphalan-dexamethasone or cyclophosphamide-bortezomib-dexamethasone. Daratumumab appears to be highly active in AL amyloidosis. Antibodies designed to dissolve existing amyloid deposits are under study.

FUTURE CHALLENGES

Delayed diagnosis remains a major obstacle to initiating effective therapy.

EDUCATIONAL OBJECTIVES

Upon completion of this educational activity, participants will be better able to: Master recognition of clinical presentations that should raise suspicion of amyloidosis. Understand simple techniques for confirming the diagnosis and providing material to classify the protein subunit. Recognize that a tissue diagnosis of amyloidosis does not indicate whether the amyloid is systemic or of immunoglobulin light chain origin. Understand the roles of the newly introduced chemotherapeutic and investigational antibody regimens for the therapy of light chain amyloidosis.

MALDI Mass Spectrometry Imaging: A Novel Tool for the Identification and Classification of Amyloidosis

Amyloidosis is a group of diseases caused by extracellular accumulation of fibrillar polypeptide aggregates. So far, diagnosis is performed by Congo red staining of tissue sections in combination with polarization microscopy. Subsequent identification of the causative protein by immunohistochemistry harbors some difficulties regarding sensitivity and specificity. Mass spectrometry based approaches have been demonstrated to constitute a reliable method to supplement typing of amyloidosis, but still depend on Congo red staining. In the present study, we used matrix-assisted laser desorption/ionization mass spectrometry imaging coupled with ion mobility separation (MALDI-IMS MSI) to investigate amyloid deposits in formalin-fixed and paraffin-embedded tissue samples. Utilizing a novel peptide filter method, we found a universal peptide signature for amyloidoses. Furthermore, differences in the peptide composition of ALλ and ATTR amyloid were revealed and used to build a reliable classification model. Integrating the peptide filter in MALDI-IMS MSI analysis, we developed a bioinformatics workflow facilitating the identification and classification of amyloidosis in a less time and sample-consuming experimental setup. Our findings demonstrate also the feasibility to investigate the amyloid's protein composition, thus paving the way to establish classification models for the diverse types of amyloidoses and to shed further light on the complex process of amyloidogenesis.

Amyloidosis: Insights from Proteomics

Amyloidoses are a spectrum of disorders caused by abnormal folding and extracellular deposition of proteins. The deposits lead to tissue damage and organ dysfunction, particularly in the heart, kidneys, and nerves. There are at least 30 different proteins that can cause amyloidosis. The clinical management depends entirely on the type of protein deposited, and thus on the underlying pathogenesis, and often requires high-risk therapeutic intervention. Application of mass spectrometry-based proteomic technologies for analysis of amyloid plaques has transformed the way amyloidosis is diagnosed and classified. Proteomic assays have been extensively used for clinical management of patients with amyloidosis, providing unprecedented diagnostic and biological information. They have shed light on the pathogenesis of different amyloid types and have led to identification of numerous new amyloid types, including ALECT2 amyloidosis, which is now recognized as one of the most common causes of systemic amyloidosis in North America.

Immunoglobulin light chain amyloidosis: 2016 update on diagnosis, prognosis, and treatment

DISEASE OVERVIEW

Immunoglobulin light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of immunoglobulin light chain are deposited in tissues. Clinical features depend on organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic failure, peripheral/autonomic neuropathy, and atypical multiple myeloma.

DIAGNOSIS

Tissue biopsy stained with Congo red demonstrating amyloid deposits with applegreen birefringence is required for diagnosis. Invasive organ biopsy is not required because amyloid deposits can be found in bone marrow biopsy or subcutaneous fat aspirate in 85% of patients. Verification that amyloid is composed of immunoglobulin light chains is mandatory.

PROGNOSIS

N-terminal pro-brain natriuretic peptide (NTproBNP), serum troponin T, and difference between involved and uninvolved immunoglobulin free light chain values are used to classify patients into four groups of similar size; median survivals are 94.1, 40.3, 14.0, and 5.8 months.

THERAPY

All patients with a systemic amyloid syndrome require therapy to prevent deposition of amyloid in other organs and prevent progressive organ failure of involved sites. Stem cell transplant (SCT) is preferred, but only 20% of patients are eligible. Requirements for safe SCT include systolic blood pressure >90 mmHg, troponin T <0.06 ng mL21, age <70 years, and serum creatinine 1.7 mg dL21. Nontransplant candidates can be offered melphalan-dexamethasone or cyclophosphamide-bortezomib-dexamethasone. Other combinations of chemotherapy with agents such as cyclophosphamide-thalidomide (or lenalidomide)-dexamethasone, bortezomib-dexamethasone, and melphalan-prednisone-lenalidomide have documented activity. Antibodies designed to dissolve existing amyloid deposits are under study for previously treated and untreated patients. Late diagnosis remains a major obstacle to initiating effective therapy. Am. J. Hematol., 2016. © 2016 Wiley Periodicals, Inc. Am. J. Hematol. 91:948-956, 2016. © 2016 Wiley Periodicals, Inc.

Immunoglobulin light chain amyloidosis: 2014 update on diagnosis, prognosis, and treatment

DISEASE OVERVIEW

Immunoglobulin light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of immunoglobulin light chain are deposited in tissues. Clinical features depend on organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic failure, peripheral/autonomic neuropathy, and atypical multiple myeloma.

DIAGNOSIS

Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for diagnosis. Invasive organ biopsy is not required because amyloid deposits can be found in bone marrow biopsy or subcutaneous fat aspirate in 85% of patients. Verification that amyloid is composed of immunoglobulin light chains is mandatory.

PROGNOSIS

N-terminal pro-brain natriuretic peptide (NT-proBNP), serum troponin T, and difference between involved and uninvolved immunoglobulin free light chain values are used to classify patients into four groups of similar size; median survivals are 94.1, 40.3, 14.0, and 5.8 months.

THERAPY

All patients with a systemic amyloid syndrome require therapy to prevent deposition of amyloid in other organs and prevent progressive organ failure of involved sites. Stem cell transplant (SCT) is preferred, but only 20% of patients are eligible. Requirements for safe SCT include NT-proBNP <5,000 ng/mL, troponin T <0.06 ng/mL, age <70 years, <3 organs involved, and serum creatinine ≤1.7 mg/dL. Nontransplant candidates can be offered melphalan-dexamethasone or cyclophosphamide-bortezomib-dexamethasone. Other combinations of chemotherapy with agents such as cyclophosphamide-thalidomide (or lenalidomide)-dexamethasone, bortezomib-dexamethasone, and melphalan-prednisone-lenalidomide have documented activity. Future Challenges: Late diagnosis remains a major obstacle to initiating effective therapy. Recognizing the presenting syndromes is necessary for improving survival.

Primary cutaneous amyloidoma: a case report

Amyloidoma is defined as solitary, localized, tumor-like deposit of amyloid in diverse organs without evidence of systemic amyloidosis. Here we report the case of a 49-year-old male patient with a solitary amyloidoma of the skin seated on the left upper lip. Full medical examination showed no signs of systemic amyloidosis. The mass was removed surgically with tangential shave and so far no signs of recurrence have been found.

AA amyloidosis: pathogenesis and targeted therapy

The understanding of why and how proteins misfold and aggregate into amyloid fibrils has increased considerably during recent years. Central to amyloid formation is an increase in the frequency of the β-sheet structure, leading to hydrogen bonding between misfolded monomers and creating a fibril that is comparably resistant to degradation. Generation of amyloid fibrils is nucleation dependent, and once formed, fibrils recruit and catalyze the conversion of native molecules. In AA amyloidosis, the expression of cytokines, particularly interleukin 6, leads to overproduction of serum amyloid A (SAA) by the liver. A chronically high plasma concentration of SAA results in the aggregation of amyloid into cross-β-sheet fibrillar deposits by mechanisms not fully understood. Therefore, AA amyloidosis can be thought of as a consequence of long-standing inflammatory disease. This review summarizes current knowledge about AA amyloidosis. The systemic amyloidoses have been regarded as intractable conditions, but improvements in the understanding of fibril composition and pathogenesis over the past decade have led to the development of a number of different therapeutic approaches with promising results.

Recent advances in transthyretin amyloidosis therapy

Mutant (MT) forms of transthyretin (TTR) cause the most common type of autosomal-dominant hereditary systemic amyloidosis-familial amyloidotic polyneuropathy (FAP). Until 20 years ago, FAP was thought to be an endemic disease, but FAP is known to occur worldwide. To date, more than 130 mutations in the TTR gene have been reported. Genotype-phenotype correlations are seen in FAP, and some variation in clinical presentation is often observed in individual kindreds with the same mutation and even among family members. Of the pathogenic TTR mutations, Val30Met was the first to be identified and is the most frequent known mutation found throughout the world. Studies of patients with FAP amyloidogenic TTR (ATTR) Val30Met documented sensorimotor polyneuropathy, autonomic dysfunction, heart and kidney failure, gastrointestinal tract (GI) disorders, and other symptoms leading to death, usually within 10 years of the onset of disease. Diagnosis is sometimes delayed, especially in patients without a clear family history and typical clinical manifestations, since diagnosis requires various studies and techniques such as histopathology, genetic testing, and mass spectrometry. For treatment of FAP, liver transplantation (LT) reportedly halts the progression of clinical manifestations. Exchange of an FAP patient's diseased liver with a healthy liver causes MT TTR in the body to be replaced by wild-type (WT) TTR. Although clinical evaluations indicated that progression of other clinical symptoms such as peripheral neuropathy, GI symptoms, and renal involvement usually halted after LT in FAP ATTR Val30Met patients, recent studies suggested that LT failed to prevent progression of cardiac amyloidosis in FAP ATTR Val30Met patients after LT, with this failure reportedly being due to continued formation of amyloid that derived mainly from WT TTR secreted from the transplanted non-mutant liver graft. In recent years, many therapeutic strategies have been proposed, and several ongoing therapeutic trials involve, for example, stabilizers of TTR tetramers (tafamidis and diflunisal) and gene therapies to suppress TTR expression (antisense methods and use of small interfering RNAs). These novel therapies may prove to prevent progression of FAP.

Immunoglobulin light chain amyloidosis: 2013 update on diagnosis, prognosis, and treatment

DISEASE OVERVIEW

Immunoglobulin (Ig) light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of Ig light chain are deposited in tissues. Clinical features depend on organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic failure, peripheral/autonomic neuropathy, and atypical multiple myeloma.

DIAGNOSIS

Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for diagnosis. Invasive organ biopsy is not required because amyloid deposits can be found in bone marrow biopsy or subcutaneous fat aspirate in 85% of patients. Verification that amyloid is of immunoglobulin origin is mandatory.

PROGNOSIS

N-terminal pro-brain natriuretic peptide (NT-proBNP), serum troponin T, and immunoglobulin free light chain values are used to classify patients into four groups of similar size; median survivals are 94.1, 40.3, 14.0, and 5.8 months.

THERAPY

All patients with a visceral amyloid syndrome require therapy to prevent deposition of amyloid in other viscera and prevent progressive organ failure of involved sites. Stem cell transplant (SCT) is preferred, but only 20% of patients are eligible. Requirements for safe SCT include NT-proBNP <5,000 ng/mL, troponin T < 0.06 ng/mL, age <70 years, <3 organs involved, and serum creatinine ≤1.7 mg/dL. Nontransplant candidates can be offered melphalan-dexamethasone. Pomalidomide appears to have activity, as do other combinations of chemotherapy with agents such as cyclophosphamide-thalidomide (or lenalidomide or bortezomib)-dexamethasone, bortezomib-dexamethasone, and melphalan-prednisone-lenalidomide.

FUTURE CHALLENGES

Late diagnosis remains a major obstacle to initiating effective therapy when organ dysfunction is still recoverable. Recognizing the presenting syndromes is necessary for improving survival.

Systemic AA amyloidosis

Systemic AA amyloidosis is a rare complication of chronic inflammatory disorders. The amyloid fibrils are derived from serum amyloid A protein, an acute phase protein synthesized in the liver. Clinical presentation is most commonly due to the consequences of renal involvement, with proteinuria and progressive renal decline. Progression to end stage renal failure is common. Management is currently centred on reducing the supply of the precursor protein by treating the underlying inflammatory condition, whilst supporting the affected organs. Monitoring of the serum amyloid A protein is vital to assess whether there is adequate suppression of the underlying disease. The level of serum amyloid A protein is a powerful predictor of both patient survival and renal outcome. In patients with adequate suppression of the serum amyloid A protein amyloid deposits can be seen to regress and renal function can be stabilised and even improve.

2011 consensus statement on endomyocardial biopsy from the Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology

The Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology have produced this position paper concerning the current role of endomyocardial biopsy (EMB) for the diagnosis of cardiac diseases and its contribution to patient management, focusing on pathological issues, with these aims: • Determining appropriate EMB use in the context of current diagnostic strategies for cardiac diseases and providing recommendations for its rational utilization • Providing standard criteria and guidance for appropriate tissue triage and pathological analysis • Promoting a team approach to EMB use, integrating the competences of pathologists, clinicians, and imagers.

Proteomic typing of amyloid deposits in systemic amyloidoses

Amyloidoses are characterized by the presence of extracellular amyloid deposits, constituted by fibrillar aggregates of misfolded proteins. Despite the similar morphologic appearance of fibrils, at least 28 different proteins have been detected as causative agents of human amyloidoses, 14 of which associated with systemic forms. Unequivocal typing of the amyloid deposits is a key step in the management of these diseases. Existing drawbacks of traditional, immunohistochemistry-based techniques have driven the search for alternative solutions for direct amyloid typing. Proteomics indicates the comprehensive study of the proteins in a biological sample, centered on analysis by mass spectrometry. The great potential of this approach in describing the composition of amyloid deposits and in studying the molecular features of the amyloidogenic precursors has become immediately clear and the introduction of proteomics in the clinical practice has revolutionized the field of amyloid typing. This review provides a critical overview of the various approaches that have been proposed in this specific context, along with a brief description of the proteomic methods for assessment of the circulating amyloidogenic proteins.

Immunohistochemistry in the classification of systemic forms of amyloidosis: a systematic investigation of 117 patients

Amyloidoses are characterized by organ deposition of misfolded proteins. This study evaluated immunohistochemistry as a diagnostic tool for the differentiation of amyloid subentities, which is warranted for accurate treatment. A total of 117 patients were systematically investigated by clinical examination, laboratory tests, genotyping, and immunohistochemistry on biopsy specimens. Immunohistochemistry enabled the classification in 94% of the cases. For subsequent analysis, the patient population was divided into 2 groups. The first group included all patients whose diagnosis could be verified by typical clinical signs or an inherited amyloidogenic mutation. In this group, immunohistochemical subtyping was successful in 49 of 51 cases and proved accurate in each of the 49 cases, corresponding to a sensitivity of 96% and a specificity of 100%. The second group included patients with systemic light chain amyloidosis without typical signs, senile transthyretin, or hereditary amyloidosis with a concomitant monoclonal gammopathy. Immunohistochemistry allowed to define the subentities in 61 of 66 (92%) of these cases. Immunohistochemistry performed by a highly specialized pathologist combined with clinical examination and genotyping leads to a high accuracy of amyloidosis classification and is the standard in our center. However, new techniques, such as mass spectroscopy-based proteomics, were recently developed to classify inconclusive cases.

Renal amyloidosis revisited: amyloid distribution, dynamics and biochemical type

BACKGROUND

Renal amyloidosis results from protein misfolding and leads to progressive renal insufficiency. Few data are available concerning the relevance of the histomorphological patterns and the dynamics of the disease process.

METHODS

Cases of renal amyloidosis in native kidney biopsies (n = 203) were retrospectively evaluated for the pattern of amyloid distribution, the extent of glomerular amyloid deposition and the amount of interstitial fibrosis and tubular atrophy. One hundred and fifty-eight cases were characterized by immunohistochemistry to determine the biochemical amyloid type. Morphological findings were correlated with available clinical data.

RESULTS

According to the predominant site of amyloid deposition, 84.6% showed a glomerular, 9.4% a vascular and 6% a tubulointerstitial distribution pattern. Within the glomeruli, amyloid was initially deposited in a focal segmental fashion that became diffuse and global in later stages. Most cases were identified as AL lambda (84/158) or AA (68/158). There was no correlation between the biochemical type and the distribution pattern. Serum creatinine correlated well with interstitial fibrosis and tubular atrophy and proteinuria with the glomerular amyloid load.

CONCLUSIONS

The relevance of the different distribution patterns is unclear at the moment, but they may be due to the physicochemical properties of the amyloid fibrils in a given patient. This may become important in future anti-fibrillar therapies.

Immunoglobulin light chain amyloidosis: 2011 update on diagnosis, risk-stratification, and management

Immunoglobulin (Ig) light chain amyloidosis is a clonal but nonproliferative plasma cell disorder in which fragments of an Ig light chain are deposited in tissues. The clinical features depend on the organs involved but can include restrictive cardiomyopathy, nephrotic syndrome, hepatic failure, and peripheral/autonomic neuropathy. Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for diagnosis. Invasive organ biopsy is not required because amyloid deposits can be found in bone marrow biopsy or subcutaneous fat aspirate in 85% of patients. N-terminal pro-brain natriuretic peptide and serum troponin T values are used to classify patients into three groups of approximately equal size; median survivals are 26.4, 10.5, and 3.5 months, respectively. All patients with a visceral amyloid syndrome require therapy to prevent deposition of amyloid in other viscera and to prevent progressive organ failure of involved sites. Stem cell transplant (SCT) is a preferred technique, but only 20% of patients are eligible. Requirements for safe SCT include mild or no cardiac involvement, troponin T value <0.06 ng/mL, age younger than 70 years, <3 organs involved, and serum creatinine value ≤1.7 mg/dL. Nontransplant candidates can be offered melphalan-dexamethasone. Pomalidomide appears to have activity, as do other combinations of chemotherapy with agents such as cyclophosphamide-thalidomide-dexamethasone, bortezomib-dexamethasone, and melphalan-prednisone-lenalidomide. Late diagnosis remains a major obstacle to initiating effective therapy when organ dysfunction is still recoverable. Recognizing the presenting syndromes is necessary for improvement in survival.

Oral Masses in Two Cats

Incisional biopsies from the oral cavity of 2 adult cats were submitted for histological investigation. Cat No. 1 showed a solitary well-circumscribed neoplasm in the left mandible. Cat No. 2 demonstrated a diffusely infiltrating neoplasm in the left maxilla. Both tumors consisted of medium-size epithelial cells embedded in a fibrovascular stroma. The mitotic index was 0 to 1 mitosis per high-power field. The epithelial cells showed an irregular arrangement forming nests or streams in cat No. 1, whereas a palisading growth was noted in cat No. 2. Both tumors, especially that of cat No. 1, showed multifocal accumulations of amyloid as confirmed by Congo red staining and a distinct green birefringence under polarized light, which lacked cytokeratin immunoreactivity as well as and AL and AA amyloid immunoreactivity. In addition, the amyloid in cat No. 2 was positive for the odontogenic ameloblast-associated protein, formerly termed APin. In sum, both cats suffered from an amyloid-producing odontogenic tumor, but their tumors varied with respect to morphology and type of amyloid produced.

Annexin A1: a central player in the anti-inflammatory and neuroprotective role of microglia

The brain microenvironment is continuously monitored by microglia with the detection of apoptotic cells or pathogens being rapidly followed by their phagocytosis to prevent inflammatory responses. The protein annexin A1 (ANXA1) is key to the phagocytosis of apoptotic leukocytes during peripheral inflammatory resolution, but the pathophysiological significance of its expression in the CNS that is restricted almost exclusively to microglia is unclear. In this study, we test the hypothesis that ANXA1 is important in the microglial clearance of apoptotic neurons in both noninflammatory and inflammatory conditions. We have identified ANXA1 to be sparingly expressed in microglia of normally aged human brains and to be more strongly expressed in Alzheimer's disease. Using an in vitro model comprising microglial and neuronal cell lines, as well as primary microglia from wild-type and ANXA1 null mice, we have identified two distinct roles for microglial ANXA1: 1) controlling the noninflammatory phagocytosis of apoptotic neurons and 2) promoting resolution of inflammatory microglial activation. In particular, we showed that microglial-derived ANXA1 targets apoptotic neurons, serving as both an "eat me" signal and a bridge between phosphatidylserine on the dying cell and formyl peptide receptor 2 on the phagocytosing microglia. Moreover, inflammatory activation of microglia impairs their ability to discriminate between apoptotic and nonapoptotic cells, an ability restored by exogenous ANXA1. We thus show that ANXA1 is fundamental for brain homeostasis, and we suggest that ANXA1 and its peptidomimetics can be novel therapeutic targets in neuroinflammation.

Trigeminal neuropathy from perineural spread of an amyloidoma detected by blink reflex and thin-slice magnetic resonance imaging

The purpose of this study was to describe a trigeminal neuropathy caused by the perineural spread of an amyloidoma. A 62-year-old woman had an amyloidoma of the Gasserian ganglion that was hypointense on T2-weighted images; the lesion was enhanced by gadolinium on thin-slice magnetic resonance imaging. There was no evidence of systemic amyloidosis or underlying inflammatory or neoplastic disorders. Her blink reflex and thin-slice magnetic resonance imaging demonstrated that the right trigeminal nerve was involved. A rare trigeminal neuropathy resulted from the perineural spread of a primary amyloidoma that was difficult to detect by conventional magnetic resonance imaging.

A proposed histopathologic classification, scoring, and grading system for renal amyloidosis: standardization of renal amyloid biopsy report

CONTEXT

A disease associated with amyloid deposits, called amyloidosis, is associated with characteristic electron microscopic appearance, typical x-ray pattern, and specific staining. Renal involvement mainly occurs in AA amyloidosis and AL amyloidosis and usually progresses to renal failure.

OBJECTIVE

The renal histopathologic changes with amyloidosis comprise a spectrum. Clear relationships between the extent of amyloid deposition and the severity of clinical manifestations have not been demonstrated. Whether there is a lack of clinicopathologic correlation is not clear, but studies have revealed the need for standardization of the renal amyloid biopsy report. With these objectives in mind, we proposed a histopathologic classification, scoring, and grading system. Renal amyloidosis was divided into 6 classes, similar to the classification of systemic lupus erythematosus. Amyloid depositions and other histopathologic lesions were scored. The sum of these scores was termed the renal amyloid prognostic score and was divided into 3 grades.

DATA SOURCES

AA amyloidosis was detected in 90% of cases, mostly related to familial Mediterranean fever. Positive correlations between class I and grade I, class VI and grade III, and class III and grade II were observed. Also, a positive correlation was identified between severity of glomerular amyloid depositions, interstitial fibrosis, and inflammation. Because of the inadequacy of the patients' records and outcomes, different therapy regimes, and etiologies, clinical validation of this study has not been completed.

CONCLUSIONS

Standardization of the renal amyloid pathology report might be critical for patients' medication and comparison of outcome and therapeutic trials between different clinics. Because of our AA to AL amyloidosis ratio and the predisposition of familial Mediterranean fever-related AA amyloidosis, there is a need for further international collaborative studies.

Amyloidosis-where are we now and where are we heading?

CONTEXT

Amyloidoses are disorders of diverse etiology in which deposits of abnormally folded proteins share distinctive staining properties and fibrillar ultrastructural appearance. Amyloidosis ultimately leads to destruction of tissues and progressive disease. With recent advances in the treatment of systemic amyloidoses the importance of an early diagnosis of amyloid, and a correct diagnosis of its type, has been realized.

OBJECTIVE

To summarize current recommendations for the diagnosis of amyloidosis.

DATA SOURCES

Presentation given at the 4th Annual Renal Pathology Society Satellite meeting in Istanbul based on discussions and recommendations formulated during an interactive diagnostic session held at the XIth International Symposium on Amyloidosis in Woods Hole, Massachusetts.

CONCLUSIONS

Congo red stain is currently the gold standard for amyloid detection and the goal is to detect amyloid early. Diagnosis of the amyloid type must be based on the identification of amyloid protein within the deposits and not solely by reliance on clinical or DNA studies. However, the latter are recommended for confirmation of the amyloid type based on evaluation of the protein in deposits. Immunohistochemistry must be performed and interpreted with caution and inconclusive results must be evaluated further using the more sophisticated methods available in referral centers. An adequate amount and quality of tissue must be available for amyloid diagnosis and typing with emphasis on the use of fresh tissue and greater use of abdominal fat biopsy. The development of new technologies underscores the need for regular review of recommendations and standards for the clinical diagnosis of amyloidosis.

Liver transplantation and combined liver-heart transplantation in patients with familial amyloid polyneuropathy: a single-center experience

Liver transplantation (LT) is the only curative option for patients with familial amyloid polyneuropathy (FAP) at present. Twenty patients with FAP underwent LT between May 1998 and June 2007. Transthyretin mutations included predominantly the Val30Met mutation but also 10 other mutations. Seven patients received a pacemaker prior to LT, and because of impairment of mechanical cardiac function, 4 combined heart-liver transplants were performed, 1 simultaneously and 3 sequentially. The first patient, who underwent simultaneous transplantation, died. Seven patients died after LT, with 5 dying within the first year after transplantation. The causes of death were cardiac complications (4 patients), infections (2 patients), and malnutrition (1 patient). One-year survival was 75.0%, and 5-year survival was 64.2%. Gly47Glu and Leu12Pro mutations showed an aggressive clinical manifestation: 2 patients with the Gly47Glu mutation, the youngest patients of all the non-Val30Met patients, suffered from severe cardiac symptoms leading to death despite LT. Two siblings with the Leu12Pro mutation, who presented only with grand mal seizures, died after LT because of sepsis. In conclusion, the clinical course in patients with FAP is very variable. Cardiac symptoms occurred predominantly in patients with non-Val30Met mutations and prompted combined heart-liver transplantation in 4 patients. Although early LT in Val30Met is indicated in order to halt the typical symptoms of polyneuropathy, additional complications occurring predominantly with other mutations may prevail and lead to life-threatening complications or a fatal outcome. Combined heart-liver transplantation should be considered in patients with restrictive cardiomyopathy.

ALkappa(I) (UNK) - primary structure of an AL-amyloid protein presenting an organ-limited subcutaneous nodular amyloid syndrome of long duration. Case report and review

Slowly progressing subcutaneous nodules all over the body were detected in 1994 in an otherwise healthy, now 66-year-old woman (UNK). A first biopsy was taken 10 years ago and revealed amyloid. Immunohistochemistry was suggestive for ALkappa. From a nodular excisate, performed in the same year for cosmetic reasons, amyloid fibrils were extracted. Protein separation according to their size revealed multiple protein fragments below the MW of an intact kappa-light chain. They were identified as kappa-fragments by Western blotting. The kappa-fragments were cleaved into overlapping peptides using tryptic, N-Asp and chymotryptic digests. Peptides were sequenced by Edman-degradation and mass spectrometry. The complete amino acid sequence of the variable region and most of the constant region of ALkappa (UNK) was identified in various fragments comprising positions 1 to 207 of a monoclonal kappa(I)-light chain. Four novel and several rare amino acid exchanges have been identified as compared to 17 amyloidogenic and >100 non-amyloidogenic kappa(I)-sequences published, leading to increased hydrophobicity of ALkappa (UNK). Sequence analysis of C-region peptides allowed one to determine the kappa-allotype as being invb(+). A rabbit antibody was produced against ALkappa(I) (UNK). It strongly reacted with amyloid on formalin-fixed paraffin embedded tissue sections of the same patient and detected ALkappa-amyloid of many other patients. In contrast, antibodies produced against kappaBJP of subclasses kappa(I)-kappa(IV) failed to label ALkappa (UNK) amyloid deposits. The patient continues to be free of systemic disease, already for 14 years until today.

Structural typing of systemic amyloidoses by luminescent-conjugated polymer spectroscopy

Most systemic amyloidoses are progressive and lethal, and their therapy depends on the identification of the offending proteins. Here we report that luminescent-conjugated thiophene polymers (LCP) sensitively detect amyloid deposits. The heterodisperse polythiophene acetic acid derivatives, polythiophene acetic acid (PTAA) and trimeric PTAA, emitted yellow-red fluorescence on binding to amyloid deposits, whereas chemically homogeneous pentameric formic thiophene acetic acid emitted green-yellow fluorescence. The geometry of LCPs modulates the spectral composition of the emitted light, thereby reporting ligand-induced steric changes. Accordingly, a screen of PTAA-stained amyloid deposits in histological tissue arrays revealed striking spectral differences between specimens. Blinded cluster assignments of spectral profiles of tissue samples from 108 tissue samples derived from 96 patients identified three nonoverlapping classes, which were found to match AA, AL, and ATTR immunotyping. We conclude that LCP spectroscopy is a sensitive and powerful tool for identifying and characterizing amyloid deposits.

Alkali-degradation of amyloid: an ancient method useful for making monoclonal antibodies against amyloid fibril proteins

The systemic amyloidoses constitute a group of life-threatening disorders at which one out of about 15 different proteins have polymerized into fibrils. Prognosis and treatment varies widely and depends on the biochemical type. Determination of this has usually to be performed by immunohistochemistry which is a challenge because of lack of monospecific antibodies that can be used on formaldehyde-fixed tissue sections. We have here used an old method to create immunogenic fragments of AL-amyloid fibrils by partial degradation and solubilization with sodium hydroxide. The mouse monoclonal antibody pwlam raised against this material, labelled AL-amyloid deposits of lambda origin strongly and specifically in sections of formaldehyde-fixed and paraffin-embedded tissues.

Isolation and characterization of monoclonal antibodies against bovine serum amyloid A1 protein

Bovine AA amyloidosis is the most frequently encountered amyloid type in cattle, and it is characterized by an extracellular deposition of pathological amyloid A (AA) protein. Because of the lack of a specific monoclonal antibody (mAbs) against bovine amyloid A (bAA) protein and its precursor, bovine serum amyloid A1 (bSAA1), at present anti-bAA rabbit antiserum and anti-human AA or SAA mAbs are widely used for diagnosis and analysis of bovine AA amyloidosis. In this study, three specific mAbs against bSAA1 were isolated by immunization using synthetic peptides of bSAA1, and these mAbs showed higher detection ability and specificity to bAA and bSAA1 than rabbit antiserum and anti-human AA or SAA mAbs in Western blot analysis and immunohistochemistry. These novel mAbs will be valuable in the development of a more precise immunochemical diagnostic tool for bovine AA amyloidosis, as well as for studying the pathophysiological mechanisms involved in this disease.

[Amyloid centers in Europe: the EURAMY project]

The systemic amyloidoses comprise a large group of serious protein deposition diseases. Although rather rare, the disorders are spread all over the world. Increasing understanding of pathogenic mechanisms and recent hope for treatment options demand further research and development of diagnostic procedures. The European Union Framework 6 program EURAMY (http://www.EURAMY.org) is devoted to all aspects of research on systemic amyloidoses, from molecular aspects to treatment of patients.