Amyloid deposits and amyloidosis. The beta-fibrilloses (first of two parts)

Current and future circulating biomarkers for cardiac amyloidosis

Cardiac amyloidosis (CA) comprises a heterogeneous group of medical conditions affecting the myocardium. It presents with proteinaceous infiltration with variable degrees of severity, prevalence and evolution. Despite this heterogeneity, erroneous protein folding is the common pathophysiologic process, yielding the formation of a single misfolded protein (monomer) that progressively evolves and ultimately forms amyloid fibers. Additionally, by seeding out from the organs of origin, intermediates called oligomers metastasize and restart the process. Such self-echoing behavior makes the secondary affected organs as important as the primary ones. Unfortunately, CA can be clinically challenging and only suggestive in a late stage of its natural history, leaving a narrow therapeutic time window available. In light of the evolutionary nature of amyloidosis, here, we propose a new classification of the currently used biomarkers based on time stages with different specificity and applicability across CA subtypes. Early markers (free light chains, serum amyloid A, β2-microglobulin, osteopontin and osteoprotegerin) can be employed for disease detection. Intermediate markers [soluble suppression of tumorigenicity 2 (sST-2), midregional proadrenomedullin (MR-proADM), von Willebrand factor (vWF), hepatocyte growth factor (HGF), matrix metalloproteinases (MMPs) and tissue inhibitor metalloproteinases (TIMPs)] can provide information on the biological mechanisms of myocardial damage. As in heart failure, late-stage biomarkers (troponins and natriuretic peptides) can help clinicians with prognosis and therapeutic response evaluation in CA. Such findings have generated a remarkable foundation for our current knowledge on CA. Nevertheless, we envision a future class of biomarkers targeted at upstream events capable of detecting folding defects, which will ultimately expand the therapeutic window.

Endoscopic Treatment of Amyloidosis of the Nasopharynx

Amyloidosis of the nasopharynx is a rare presentation of localized amyloidosis. The majority of systemic amyloidosis cases involve the heart, gastrointestinal tract, kidneys, and upper and lower respiratory tract. Localized amyloidosis involving only one site is less common, but has been observed in the head and neck area, particularly in the larynx or the oral cavity. Amyloidosis in the nasopharynx has been reported in only seven previous cases in the English literature.

Confinement-induced liquid crystalline transitions in amyloid fibril cholesteric tactoids

Chirality is ubiquitous in nature and plays crucial roles in biology, medicine, physics and materials science. Understanding and controlling chirality is therefore an important research challenge with broad implications. Unlike other chiral colloids, such as nanocellulose or filamentous viruses, amyloid fibrils form nematic phases but appear to miss their twisted form, the cholesteric or chiral nematic phases, despite a well-defined chirality at the single fibril level. Here we report the discovery of cholesteric phases in amyloids, using β-lactoglobulin fibrils shortened by shear stresses. The physical behaviour of these new cholesteric materials exhibits unprecedented structural complexity, with confinement-driven ordering transitions between at least three types of nematic and cholesteric tactoids. We use energy functional theory to rationalize these results and observe a chirality inversion from the left-handed amyloids to right-handed cholesteric droplets. These findings deepen our understanding of cholesteric phases, advancing their use in soft nanotechnology, nanomaterial templating and self-assembly.

Response of Bortezomib Chemotherapy in Hepatic Amyloidosis

Amyloidosis is a rare disorder with a wide spectrum of presentations and anomalies. It is subdivided into 2 broad categories based on protein deposition; primary and secondary amyloidosis. It can present as a single-organ involvement or as a diffuse infiltrative multi-organ process. Isolated hepatic amyloidosis presentation is a rare phenomenon that develops due to insoluble amyloid deposition in liver. Its clinical presentation is usually vague and ranges from mild hepatomegaly with elevated liver enzymes to acute liver failure and hepatic rupture. Currently, there are scarce data available regarding treatment options for biopsy-proven hepatic amyloidosis. In this review article, we present an interesting case of hepatic amyloidosis and its poor outcome to new molecular targeted chemotherapy. Furthermore, we aim to review current and future diagnostic tools for early detection and advancements in targeted chemotherapeutics options available for hepatic amyloidosis.

Serum Alpha-1-Antitrypsin in Hemodialysis Patients with Dialysis Arthropathy

Dialysis arthropathy is the most prominent dialysis-related amyloidosis feature. Alpha-1-antitrypsin (alpha-1-proteinase inhibitor) is the major circulating antiprotease. Twenty-three otherwise uncomplicated hemodialysis patients with well-documented dialysis arthropathy had a significantly (p < 0.05) lower serum mean concentration, 1,960 ± 410.4 mg/I of alpha-1-antitrypsin than 47 patients with no joint symptoms who had a mean concentration of 2,256.6 ± 424.5 mg/I. Decreased levels of the substance were detected in 13 (56.5%) of the 23 patients with dialysis arthropathy and in 13 (27.6%) of those 47 with no joint symptoms, the incidence in the former group being significantly (p < 0.05) higher than in the latter. In the dialysis arthropathy group, serum alpha-1-antitrypsin levels correlated inversely (r = −0.54, p < 0.01) with the dialysis duration and directly (r = 0.413, p < 0.05) with the corresponding beta-2-microglobulin determinations. We speculate that reduced antiprotease activity may play a role in amyloidogenesis in the setting of long-term hemodialysis.

Bilateral Limbal Keratin-Associated Amyloidosis

Conjunctival amyloid is usually of the immunoglobulin light chain (AL) variety. The authors report an exceptional case of bilateral limbal amyloid deposits that were identified by mass spectrometry as keratin-related specifically regarding to basal keratinocyte keratins 5 and 14. Cytokeratin-related amyloid has been described by immunohistochemical analysis of formalin-fixed cutaneous and mucous membrane lesions but not ocular tissues. The conjunctival lesion in the right eye contained intraepithelial dyskeratotic cells that extended to the surface, causing a lacy leukoplakia on clinical examination. The authors excluded the diagnosis of hereditary benign intraepithelial dyskeratosis in this patient. Collection of patient data and all protected patient health information was compliant with the Health Insurance Portability and Accountability Act.

Imaging for abdominal involvement in amyloidosis

Involvement of the abdominal organs has variable presentations mostly without specific findings. The objective of this pictorial essay was to illustrate the computed tomography and magnetic resonance imaging (MRI) findings of abdominal involvement in systemic amyloidosis. Heterogeneous appearance of the liver, periportal involvement, diffuse low signal intensity of spleen on T2-weighted MRI, and thickened bowel wall may be helpful imaging findings when accompanied by presence or history of chronic inflammatory disease and clinical suspicion for amyloidosis.

Oligosecretory Myeloma With Amyloidosis and Alopecia

Amyloidosis is a systemic illness characterized by the extracellular deposition of abnormal proteins in body tissues and organs. In addition to renal involvement, amyloidosis can also present with a variety of skin manifestations, though rarely with alopecia. Sixteen cases of alopecia secondary to systemic amyloidosis are reported. There is one reported case that presented with alopecia universalis. We report a case of a 68-year-old woman presenting with alopecia universalis, rapid decline in kidney function, and nephrotic syndrome who was found to have multiple myeloma-associated AL amyloidosis (immunoglobulin light chain). Her serological workup including serum electrophoresis was negative and she underwent renal biopsy. Pathology revealed eosinophilic material within the mesangium that was Congo-red positive, had apple-green birefringence under polarized light, and ultramicroscopically appeared as fibrillary material. Subsequent bone marrow examination showed a diffuse increase in plasma cells with atypia indicating plasma cell neoplasm. This case underlines several interesting aspects of multiple myeloma and the way it may present with amyloidosis. The lack of monoclonal spike on electrophoresis yet positive light chain analysis deserves special attention by clinicians to avoid a missed diagnosis. The extensive skin involvement also raises several questions regarding the pathologic mechanisms of alopecia in a patient with amyloidosis.

Co-precipitation molecules hemopexin and transferrin may be key molecules for fibrillogenesis in TTR V30M amyloidogenesis

The disease model of familial amyloidotic polyneuropathy—7.2-hMet30 mice—manifests amyloid deposition that consists of a human amyloidogenic mutant transthyretin (TTR) (TTR V30M). Our previous study found amyloid deposits in 14 of 27 7.2-hMet30 mice at 21–24 months of age. In addition, non-fibrillar TTR deposits were found in amyloid-negative 7.2hMet30 mice. These results suggested that TTR amyloidogenesis required not only mutant TTR but also an additional factor (or factors) as an etiologic molecule. To determine the differences in serum proteome in amyloid-positive and amyloid-negative mice in the 7.2-hMet30 model, we used proteomic analyses and studied serum samples obtained from these mice. Hemopexin (HPX) and transferrin (Tf) were detected in the serum samples from amyloid-positive mice and were also found in amyloid deposits via immunohistochemistry, but serum samples from amyloid-negative mice did not contain HPX and Tf. These two proteins were also not detected in non-fibrillar TTR deposits. In addition, in silico analyses suggested that HPX and Tf facilitate destabilization of TTR secondary structures and misfolding of TTR. These results suggest that HPX and Tf may be associated with TTR amyloidogenesis after fibrillogenesis in vivo.

Localized Nasopharyngeal Amyloidosis: A Clinicopathologic Series of 7 Cases with a Literature Review

Localized nasopharyngeal amyloidosis is an extremely rare entity with only 25 cases described in the English and German literature. We present a case series of seven patients with localized nasopharyngeal amyloidosis and combine the findings with a thorough review the literature.

The conformation of the Congo-red ligand bound to amyloid fibrils HET-s(218-289): a solid-state NMR study

We have previously shown that Congo red (CR) binds site specifically to amyloid fibrils formed by HET-s(218-289) with the long axis of the CR molecule almost parallel to the fibril axis. HADDOCK docking studies indicated that CR adopts a roughly planar conformation with the torsion angle ϕ characterizing the relative orientation of the two phenyl rings being a few degrees. In this study, we experimentally determine the torsion angle ϕ at the center of the CR molecule when bound to HET-s(218-289) amyloid fibrils using solid-state NMR tensor-correlation experiments. The method described here relies on the site-specific ¹³C labeling of CR and on the analysis of the two-dimensional magic-angle spinning tensor-correlation spectrum of ¹³C₂-CR. We determined the torsion angle ϕ to be 19°.

The β-cell assassin: IAPP cytotoxicity

Islet amyloid polypeptide (IAPP) forms cytotoxic oligomers and amyloid fibrils in islets in type 2 diabetes (T2DM). The causal factors for amyloid formation are largely unknown. Mechanisms of molecular folding and assembly of human IAPP (hIAPP) into β-sheets, oligomers and fibrils have been assessed by detailed biophysical studies of hIAPP and non-fibrillogenic, rodent IAPP (rIAPP); cytotoxicity is associated with the early phases (oligomers/multimers) of fibrillogenesis. Interaction with synthetic membranes promotes β-sheet assembly possibly via a transient α-helical molecular conformation. Cellular hIAPP cytotoxicity can be activated from intracellular or extracellular sites. In transgenic rodents overexpressing hIAPP, intracellular pro-apoptotic signals can be generated at different points in β-cell protein synthesis. Increased cellular trafficking of proIAPP, failure of the unfolded protein response (UPR) or excess trafficking of misfolded peptide via the degradation pathways can induce apoptosis; these data indicate that defects in intracellular handling of hIAPP can induce cytotoxicity. However, there is no evidence for IAPP overexpression in T2DM. Extracellular amyloidosis is directly related to the degree of β-cell apoptosis in islets in T2DM. IAPP fragments, fibrils and multimers interact with membranes causing disruption in vivo and in vitro These findings support a role for extracellular IAPP in β-sheet conformation in cytotoxicity. Inhibitors of fibrillogenesis are useful tools to determine the aberrant mechanisms that result in hIAPP molecular refolding and islet amyloidosis. However, currently, their role as therapeutic agents remains uncertain.

Hepatic Amyloidosis: Something That Can camouflage and Deceive our Perception!

Amyloidosis is a multi-systemic diffusely infiltrating disease due to extracellular deposition of protein-mucopolysaccharide complexes. The type of protein deposited determines the subgroup of amyloid. Hepatic amyloidosis is a rare infiltrating disease affecting the hepatic parenchyma. A wide range of clinical presentation and atypical imaging findings delay the diagnosis of amyloidosis, while tissue biopsy demonstrating amyloid deposits is vital for a definitive diagnosis.

Systemic AA amyloidosis in the red fox (Vulpes vulpes)

Amyloid A (AA) amyloidosis occurs spontaneously in many mammals and birds, but the prevalence varies considerably among different species, and even among subgroups of the same species. The Blue fox and the Gray fox seem to be resistant to the development of AA amyloidosis, while Island foxes have a high prevalence of the disease. Herein, we report on the identification of AA amyloidosis in the Red fox (Vulpes vulpes). Edman degradation and tandem MS analysis of proteolyzed amyloid protein revealed that the amyloid partly was composed of full-length SAA. Its amino acid sequence was determined and found to consist of 111 amino acid residues. Based on inter-species sequence comparisons we found four residue exchanges (Ser31, Lys63, Leu71, Lys72) between the Red and Blue fox SAAs. Lys63 seems unique to the Red fox SAA. We found no obvious explanation to how these exchanges might correlate with the reported differences in SAA amyloidogenicity. Furthermore, in contrast to fibrils from many other mammalian species, the isolated amyloid fibrils from Red fox did not seed AA amyloidosis in a mouse model.

Novel pathologic scoring tools predict end-stage kidney disease in light chain (AL) amyloidosis

BACKGROUND AND OBJECTIVES

Light chain (AL) amyloidosis frequently involves the kidney, causing significant morbidity and mortality. A pathologic scoring system with prognostic utility has not been developed. We hypothesized that the extent of amyloid deposition and degree of scarring injury on kidney biopsy, could provide prognostic value, and aimed to develop pathologic scoring tools based on these features.

METHODS

This is a case-control study of 39 patients treated for AL amyloidosis with biopsy-proven kidney involvement at a large academic medical center. Our novel scoring tools, composite scarring injury score (CSIS) and amyloid score (AS) were applied to each kidney biopsy. The primary outcome was progression to dialysis-dependent end-stage kidney disease (ESKD) using a 12-month landmark analysis.

RESULTS

At 12 months, nine patients had progressed to ESKD. Patients with an AS ≥7.5 had a significantly higher cumulative incidence of ESKD than those with AS <7.5 (p = .04, 95% CI 0.13-0.64).

CONCLUSIONS

Using a 12-month landmark analysis, AS correlated with progression to ESKD. These data suggest that a kidney biopsy, in addition to providing diagnostic information, can be the basis for a pathologic scoring system with prognostic significance.

Localized nasopharyngeal amyloidosis mimicking malignancy: A case report

RATIONALE

Nasopharyngeal amyloidosis is a benign, slowly progressive disease that is characterized by extracellular eosinophilic deposition.

PATIENT CONCERNS

We report a rare case of localized nasopharyngeal amyloidosis.

DIAGNOSES

The initial chief complaint of this patient was frequent epistaxis and right aural fullness. The initial diagnosis was nasopharyngeal tumor.

INTERVENTIONS

There is no universally effective medical treatment for nasopharyngeal amyloidosis but surgery can be an option. We performed careful observation with regular follow-up by nasopharyngoscopy and radiologic study.

OUTCOMES

The patient reported no further complaints at 1-year follow-up and the lesion from nasopharyngeal amyloidosis was still present.

LESSONS

Although it is rare, nasopharyngeal amyloidosis should be considered in the differential diagnosis of epistaxis, nasal obstruction, and otitis media with effusion, which are the main symptoms of nasopharyngeal carcinoma. In the absence of systemic disease, localized nasopharyngeal amyloidosis may be treated conservatively.

Transthyretin and BRICHOS: The Paradox of Amyloidogenic Proteins with Anti-Amyloidogenic Activity for Aβ in the Central Nervous System

Amyloid fibrils are physiologically insoluble biophysically specific β-sheet rich structures formed by the aggregation of misfolded proteins. In vivo tissue amyloid formation is responsible for more than 30 different disease states in humans and other mammals. One of these, Alzheimer's disease (AD), is the most common form of human dementia for which there is currently no definitive treatment. Amyloid fibril formation by the amyloid β-peptide (Aβ) is considered to be an underlying cause of AD, and strategies designed to reduce Aβ production and/or its toxic effects are being extensively investigated in both laboratory and clinical settings. Transthyretin (TTR) and proteins containing a BRICHOS domain are etiologically associated with specific amyloid diseases in the CNS and other organs. Nonetheless, it has been observed that TTR and BRICHOS structures are efficient inhibitors of Aβ fibril formation and toxicity in vitro and in vivo, raising the possibility that some amyloidogenic proteins, or their precursors, possess properties that may be harnessed for combating AD and other amyloidoses. Herein, we review properties of TTR and the BRICHOS domain and discuss how their abilities to interfere with amyloid formation may be employed in the development of novel treatments for AD.

Amyloidosis: A cancer-derived paraproteinemia and kidney involvement

Amyloidosis is the general term describing the extracellular tissue deposition of fibrils composed of low molecular weight subunits of a variety of proteins. There are multiple different human protein precursors of amyloid fibrils. Amyloid deposits are stained using Congo Red and show typical apple-green birefringence in polarized microscopy. Nowadays, a novel technique LMD/MS technique or laser microdissection combined with mass spectrometry help to diagnose amyloidosis. Amyloidosis of the kidney is typically classified as being either one of two types: AL or AA. Less common is the hereditary amyloidosis. Clinical manifestations are usually determined by the type of precursor protein, the tissue distribution, and the amount of amyloid deposition. Renal manifestation is usually present as asymptomatic proteinuria or clinically apparent nephrotic syndrome. In some patients clinical presentation include impaired kidney function with no or mild proteinuria. Patients with renal amyloidosis who progress to end-stage renal disease (ESRD) can be treated with either dialysis or renal transplantation. Diagnosis of amyloidosis is prerequisite to consider treatment options to avoid unnecessary chemotherapy. Treatment of amyloidosis is aimed at decreasing the precursors of fibrillary proteins and/or decrease in synthesis/deposition of amyloid fibrils. It depends upon the type of amyloidosis and cause of excess fibril production.

Potential biomarkers and novel pharmacological targets in protein aggregation-related neurodegenerative diseases

The aggregation of specific proteins plays a pivotal role in the etiopathogenesis of several neurodegenerative diseases (NDs). β-Amyloid (Aβ) peptide-containing plaques and intraneuronal neurofibrillary tangles composed of hyperphosphorylated protein tau are the two main neuropathological lesions in Alzheimer's disease. Meanwhile, Parkinson's disease is defined by the presence of intraneuronal inclusions (Lewy bodies), in which α-synuclein (α-syn) has been identified as a major protein component. The current literature provides considerable insights into the mechanisms underlying oligomeric-related neurodegeneration, as well as the relationship between protein aggregation and ND, thus facilitating the development of novel putative biomarkers and/or pharmacological targets. Recently, α-syn, tau and Aβ have been shown to interact each other or with other "pathological proteins" to form toxic heteroaggregates. These latest findings are overcoming the concept that each neurodegenerative disease is related to the misfolding of a single specific protein. In this review, potential opportunities and pharmacological approaches targeting α-syn, tau and Aβ and their oligomeric forms are highlighted with examples from recent studies. Protein aggregation as a biomarker of NDs, in both the brain and peripheral fluids, is deeply explored. Finally, the relationship between biomarker establishment and assessment and their use as diagnostics or therapeutic targets are discussed.

Nano Zinc Oxide Inhibits Fibrillar Growth and Suppresses Cellular Toxicity of Lysozyme Amyloid

Deposition of amyloid fibers has been a common pathological event in many neurodegenerations, such as Alzheimer's disease, Parkinson's disease, and Prion disease. Although various therapeutic interventions have been reported, nanoparticles have recently been considered as possible inhibitors of amyloid fibrillation. Here, we reported the effect of three different forms of zinc oxide nanoparticles (ZnONP): uncapped (ZnONP_uncap), starch-capped (ZnONP_ST), and self-assembled (ZnONP_assmb) (average sizes of 10, 30, and 163 nm, respectively), having a core size of 10-15 nm, in the amyloid growth of hen egg white lysozyme (HEWL). We monitored the amyloid growth by electron microscopy as well as Thioflavin-T (ThT) measurement. We observed that ZnONP demonstrated a dose-dependent inhibition of fibrillar amyloid growth of HEWL, with the greatest effect being exhibited by ZnONP_ST. Such inhibition was also associated with a decrease in cross β-sheet amount, surface hydrophobicity as well as increase of stability of proteins. Furthermore, we observed that ZnONP_ST prolonged the nucleation phase and shortened the elongation phase of HEWL amyloid growth. Although pure amyloid caused profound cellular toxicity in both mouse carcinoma N2a and normal cells such as human keratinocytes HaCaT cells, amyloid formed in the presence of ZnONP showed much reduced cellular toxicity. We also observed that the inhibition of amyloid growth was effective when ZnONP was administered during the lag phase. When our amyloid inhibition results were compared with a well-known inhibitor curcumin, we observed that ZnONP_ST demonstrated a better inhibitory effect than curcumin. Overall, here, we reported the inhibitory activity of three different forms of ZnONP to amyloid fibrillation of HEWL and amyloid-mediated cytotoxicity to different extents, while starch-capped ZnONP showed the highest fibrillation inhibitory effect.

The Effect of T-2 Toxin on the Acute Phase Reaction in Mice

The effects of T-2 toxin on a murine model of the acute phase response were studied. Two murine acute phase reactants, serum amyloid P component and plasma fibronectin, were measured after subcutaneous and intraperitoneal administration of T-2 toxin in varying doses. No acute phase response was observed. Furthermore, T-2 toxin also blocked the acute phase reaction to subcutaneous AgNO3 in a dose-dependent fashion. These observations were not explained by damage to liver, the site of synthesis of acute phase proteins. Since the acute phase response is an immediate physiological reaction to tissue injury and may be a nonspecific participant in the repair phenomenon, its abrogation by T-2 toxin may contribute to the toxicity of this trichothecene mycotoxin.

Magnetic Resonance Imaging in Primary Amyloidosis

Twelve patients with primary amyloidosis (AL) were investigated with magnetic resonance imaging (MRI). In 9 patients an abnormal thickening of the heart walls was present and in 2 macroglossia was found at MRI. T1 was significantly increased in liver (p<0.05) and subcutaneous fat (p<0.01) while it was decreased in the spleen (p<0.05). T2 was significantly decreased (p<0.01) in the spleen in patients with amyloidosis, while it was not significantly altered in the liver or subcutaneous fat. After therapy T1 of the liver was reduced towards normal values in 4 patients. It is concluded that MRI might be a method to quantitate the amount of amyloid deposits in the tissue, and that the effect of therapy may be monitored with this technique.

The Kinetic Stability of a Full-Length Antibody Light Chain Dimer Determines whether Endoproteolysis Can Release Amyloidogenic Variable Domains

Light chain (LC) amyloidosis (AL amyloidosis) appears to be caused by the misfolding, or misfolding and aggregation of an antibody LC or fragment thereof and is fatal if untreated. LCs are secreted from clonally expanded plasma cells, generally as disulfide-linked dimers, with each monomer comprising one constant and one variable domain. The energetic contribution of each domain and the role of endoproteolysis in AL amyloidosis remain unclear. To investigate why only some LCs form amyloid and cause organ toxicity, we measured the aggregation propensity and kinetic stability of LC dimers and their associated variable domains from AL amyloidosis patients and non-patients. All the variable domains studied readily form amyloid fibrils, whereas none of the full-length LC dimers, even those from AL amyloidosis patients, are amyloidogenic. Kinetic stability-that is, the free energy difference between the native state and the unfolding transition state-dictates the LC's unfolding rate. Full-length LC dimers derived from AL amyloidosis patients unfold more rapidly than other full-length LC dimers and can be readily cleaved into their component domains by proteases, whereas non-amyloidogenic LC dimers are more kinetically stable and resistant to endoproteolysis. Our data suggest that amyloidogenic LC dimers are kinetically unstable (unfold faster) and are thus susceptible to endoproteolysis that results in the release amyloidogenic LC fragments, whereas other LCs are not as amenable to unfolding and endoproteolysis and are therefore aggregation resistant. Pharmacologic kinetic stabilization of the full-length LC dimer could be a useful strategy to treat AL amyloidosis.

Inflammation as a Risk of Developing Chronic Kidney Disease in Rheumatoid Arthritis

Objective

The relationship between chronic inflammation and the incidence of chronic kidney disease (CKD) remained not-clear in patients with rheumatoid arthritis (RA). This study aims to examine the relationship between persistently high C-reactive protein (CRP), a marker of inflammation, and the incidence of CKD in RA.

Methods

We retrospectively examined the relationship between the levels of CRP and incidence of CKD in 345 RA patients. The outcome of interest was incidence of CKD, defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² and/or positive dipstick testing for proteinuria for ≥3 months. We defined high CRP, as >3.0 mg/L. On the basis of three measurements of CRP for 6-months period, patients were divided into three groups: group 1, including patients with no high CRP values; group 2, patients with transient high CRP values (once or twice) and group 3, patients with persistently high CRP values.

Results

During a median follow-up period of 89 months, 14% of all patients developed CKD. The cumulative incidence of CKD was 7% in group 1, 14% in group 2 and 22% in group 3 (P = 0.008, log-rank test). In a multivariate analysis, including classical risk factors for CKD, persistently high CRP was an independent predictor of the incidence of CKD (hazard ratio, 3.00; 95% confidence interval, 1.23–8.53; P = 0.01).

Conclusions

Persistently high CRP was a significant risk factor for the incidence of CKD. Results suggest that persistent inflammation is a marker for the high risk of CKD in RA.

Waldenström's Macroglobulinemia Associated With Generalized AA-Amyloidosis

The authors present a case of Waldenström's macroglobulinemia (WM) associated with generalized amyloidosis of amyloid-A type. A 77-year-old man with a 25-year history of degenerative joint disease and a 13-year history of WM died of multisystemic failure. At autopsy, generalized and severe amyloid deposits were detected. Special conventional stains and immunohistochemical examination revealed amyloid-A de posits, which are extinguishingly rare in WM. This is probably related to the disease being chronic, which results in excessive production of precursor protein. The detection of amyloid-A type fibrils was possible only through the application of the immunohis tochemical procedure. The authors emphasize using the immunohistochemical typing of amyloid deposits for the purpose of classification, therapy, and prognosis. Int J Surg Pathol 1 (2):123-128, 1993

A critical appraisal of the pathogenic protein spread hypothesis of neurodegeneration

There has been an explosion in the number of papers discussing the hypothesis of 'pathogenic spread' in neurodegenerative disease - the idea that abnormal forms of disease-associated proteins, such as tau or α-synuclein, physically move from neuron to neuron to induce disease progression. However, whether inter-neuronal spread of protein aggregates actually occurs in humans and, if so, whether it causes symptom onset remain uncertain. Even if pathogenic spread is proven in humans, it is unclear how much this would alter the specific therapeutic approaches that are in development. A critical appraisal of this increasingly popular hypothesis thus seems both important and timely.

Amyloid Arthropathy of the Hip Joint Associated with Multiple Myeloma: A Case Report

Amyloidosis is a disease characterized by the deposition of non-soluble fibrous protein in multiple tissues with a number of possible causes. This protein deposition can occur in any tissue, yet is most commonly seen in kidneys, heart, and gastrointestinal tracts. However, invasion to bone tissues is not often reported. The deposition of amyloid proteins in bone tissues may result in joint pain and pathological fractures; it is important to elucidate the causes and detect early to determine prognosis and treat optimally. In the present case report, with relevant literature review, the authors report a case of total hip arthroplasty in an amyloidosis patient.

Amyloidosis: an unusual cause of portal hypertension

Amyloidosis comprises a group of diseases that occurs in five to nine cases per million patients per year worldwide irrespective of its classification. Although the hepatic involvement in primary amyloidosis is frequent, the clinical manifestations of liver amyloidosis are mild or even absent. The authors report the case of an aged man who complained of diffuse abdominal pain and marked weight loss and presented clinical signs of hepatopathy. Clinical workup revealed portal hypertension with ascites, hemorrhoids, and esophageal varices. The laboratory tests showed the cholestatic pattern of liver enzymes, hyperbilirubinemia, renal insufficiency and massive proteinuria accompanied by the presence of serum pike of monoclonal lambda light chain protein. The outcome was unfavorable, and the patient died. The autopsy findings revealed the diagnosis of amyloidosis predominantly involving the liver and kidneys. The bone marrow examination demonstrated the deposition of amyloid material associated with clonal plasma cells infiltration. The authors call attention to portal hypertension as a rare manifestation of primary amyloidosis. Meanwhile, this diagnosis should be taken into account whenever the hepatopathy is accompanied by laboratory abnormalities consistent with hepatic space-occupying lesions concomitantly with other organs involvement. In the case reported herein, kidney involvement was also present with renal failure, massive proteinuria with monoclonal serum gammopathy, what reinforced the diagnostic possibility of primary amyloidosis.

New protein deposition tracers in the pipeline

Traditional nuclear medicine ligands were designed to target cellular receptors or transporters with a binding pocket and a defined structure-activity relationship. More recently, tracers have been developed to target pathological protein aggregations, which have less well-defined structure-activity relationships. Aggregations of proteins such as tau, α-synuclein, and β-amyloid (Aβ) have been identified in neurodegenerative diseases, including Alzheimer's disease (AD) and other dementias, and Parkinson's disease (PD). Indeed, Aβ deposition is a hallmark of AD, and detection methods have evolved from coloured dyes to modern 18F-labelled positron emission tomography (PET) tracers. Such tracers are becoming increasingly established in routine clinical practice for evaluation of Aβ neuritic plaque density in the brains of adults who are being evaluated for AD and other causes of cognitive impairment. While similar in structure, there are key differences between the available compounds in terms of dosing/dosimetry, pharmacokinetics, and interpretation of visual reads. In the future, quantification of Aβ-PET may further improve its utility. Tracers are now being developed for evaluation of tau protein, which is associated with decreased cognitive function and neurodegenerative changes in AD, and is implicated in the pathogenesis of other neurodegenerative diseases. While no compound has yet been approved for tau imaging in clinical use, it is a very active area of research. Development of tau tracers comprises in-depth characterisation of existing radiotracers, clinical validation, a better understanding of uptake patterns, test-retest/dosimetry data, and neuropathological correlations with PET. Tau imaging may allow early, more accurate diagnosis, and monitoring of disease progression, in a range of conditions. Another marker for which imaging modalities are needed is α-synuclein, which has potential for conditions including PD and dementia with Lewy bodies. Efforts to develop a suitable tracer are ongoing, but are still in their infancy. In conclusion, several PET tracers for detection of pathological protein depositions are now available for clinical use, particularly PET tracers that bind to Aβ plaques. Tau-PET tracers are currently in clinical development, and α-synuclein protein deposition tracers are at early stage of research. These tracers will continue to change our understanding of complex disease processes.

Interaction of the ginsenosides with κ-casein and their effects on amyloid fibril formation by the protein: Multi-spectroscopic approaches

The interaction of the ginsenosides (GS) including ginsenoside Rg1, Rb1 and Re with κ-casein and the effects of GS inhibiting amyloid fibril formation by κ-casein have been investigated in vitro by fluorescence and ultraviolet spectra. Results showed that Rg1 and Rb1 had dose-dependent inhibitory effects on reduced and carboxymethylated κ-casein (RCMκ-CN) fibril formation, while Re resulted in an increase in the rate of fibril formation. The enhancement in RLS intensity was attributed to the formation of new complex between GS and RCMκ-CN, and the corresponding thermodynamic parameters (ΔH, ΔS and ΔG) were assayed. The steady-state ultraviolet-visible absorption spectra had also been tested to observe if the ground-state complex formed, and it showed the same result as RLS spectra. The binding constants and the number of binding sites between GS and RCMκ-CN at different temperatures had been evaluated from relevant fluorescence data. According to the Förster non-radiation energy transfer theory, the binding distance between RCMκ-CN and GS was calculated. The fluorescence lifetime of RCMκ-CN was longer in the presence of GS than in absence of GS, which was evident that the hydrophobic interaction plays a major role in the binding of GS to RCMκ-CN. From the results of synchronous fluorescence, it could be deduced that the polarity around RCMκ-CN Trp97 residue decreased and the hydrophobicity increased after addition of Rg1 or Rb1. Based on all the above results, it is explained that Rg1 and Rb1 inhibited amyloid fibril formation by κ-casein because the molecular spatial conformation and physical property of κ-casein changed causing by the complex formation between GS and κ-casein.

Hypertension and Dementia: Epidemiological and Experimental Evidence Revealing a Detrimental Relationship

Hypertension and dementia represent two major public health challenges worldwide, notably in the elderly population. Although these two conditions have classically been recognized as two distinct diseases, mounting epidemiological, clinical and experimental evidence suggest that hypertension and dementia are strictly intertwined. Here, we briefly report how hypertension profoundly affects brain homeostasis, both at the structural and functional level. Chronic high blood pressure modifies the cerebral vasculature, increasing the risk of Aβ clearance impairment. The latter, excluding genetic etiologies, is considered one of the main causes of Aβ deposition in the brain. Studies have shown that hypertension induces cerebral arterial stiffening and microvascular dysfunction, thus contributing to dementia pathophysiology. This review examines the existing and the updated literature which has attempted to explain and clarify the relationship between hypertension and dementia at the pathophysiological level.

Asymptomatic localized pleural amyloidosis mimicking malignant pleural mesothelioma: report of a case

We herein report an asymptomatic 65-year-old male with localized pleural amyloidosis mimicking malignant pleural mesothelioma. He had a history of exposure to asbestos and was admitted for investigation of an abnormal pleural thickness detected by chest radiography. Positron emission tomography showed elevation of standardized uptake value corresponding to the pleural thickness. Partial pleurectomy including the tumor was performed for the purpose of diagnosis and local disease control. The pathological examination showed that the tumor was pleural amyloidosis. The tumor was diagnosed as localized primary amyloidosis, because serum monoclonal protein concentration did not increase. Pleural amyloidosis should be considered as a differential diagnosis from pleural mesothelioma.

Single Nodular Pulmonary Amyloidosis: Case Report

Amyloidosis is defined as the presence of extra-cellular deposits of an insoluble fibrillar protein, amyloid. The pulmonary involvement of amyloidosis is usually classified as tracheobronchial, parenchymal nodular, or diffuse alveolar septal. A single nodular lesion can mimic various conditions, including malignancy, pulmonary tuberculosis, and fungal infection. To date, only one case of nodular pulmonary amyloidosis has been reported in Korea, a case involving multiple nodular lesions. Here, we report and discuss the case of a patient having single nodular amyloidosis.

Fluorescent proteins as genetically encoded FRET biosensors in life sciences

Fluorescence- or Förster resonance energy transfer (FRET) is a measurable physical energy transfer phenomenon between appropriate chromophores, when they are in sufficient proximity, usually within 10 nm. This feature has made them incredibly useful tools for many biomedical studies on molecular interactions. Furthermore, this principle is increasingly exploited for the design of biosensors, where two chromophores are linked with a sensory domain controlling their distance and thus the degree of FRET. The versatility of these FRET-biosensors made it possible to assess a vast amount of biological variables in a fast and standardized manner, allowing not only high-throughput studies but also sub-cellular measurements of biological processes. In this review, we aim at giving an overview over the recent advances in genetically encoded, fluorescent-protein based FRET-biosensors, as these represent the largest and most vividly growing group of FRET-based sensors. For easy understanding, we are grouping them into four categories, depending on their molecular mechanism. These are based on: (a) cleavage; (b) conformational-change; (c) mechanical force and (d) changes in the micro-environment. We also address the many issues and considerations that come with the development of FRET-based biosensors, as well as the possibilities that are available to measure them.

Mechanisms of amyloid fibril formation

Amyloid and amyloid-like aggregates are elongated unbranched fibrils consisting of β-structures of separate monomers positioned perpendicular to the fibril axis and stacked strictly above each other. In their physicochemical properties, amyloid fibrils are reminiscent of synthetic polymers rather than usual proteins because they are stable to the action of denaturing agents and proteases. Their mechanical stability can be compared to a spider's web, that in spite of its ability to stretch, is stronger than steel. It is not surprising that a large number of diseases are accompanied with amyloid fibril depositing in different organs. Pathologies provoked by depositing of incorrectly folded proteins include Alzheimer's, Parkinson's, and Huntington's diseases. In addition, this group of diseases involves mucoviscidosis, some types of diabetes, and hereditary cataracts. Each type of amyloidosis is characterized by aggregation of a certain type of protein that is soluble in general, and thus leads to specific distortions of functions of the corresponding organs. Therefore, it is important to understand the process of transformation of "native" proteins to amyloid fibrils to clarify how these molecules acquire such strength and what key elements of this process determine the pathway of erroneous protein folding. This review presents our analysis of complied information on the mechanisms of formation and biochemical properties of amyloid fibrils.

Heme Stabilization of α-Synuclein Oligomers during Amyloid Fibril Formation

α-Synuclein (αSyn), which forms amyloid fibrils, is linked to the neuronal pathology of Parkinson's disease, as it is the major fibrillar component of Lewy bodies, the inclusions that are characteristic of the disease. Oligomeric structures, common to many neurodegenerative disease-related proteins, may in fact be the primary toxic species, while the amyloid fibrils exist either as a less toxic dead-end species or even as a beneficial mechanism for clearing damaged proteins. To alter the progression of the aggregation and gain insights into the prefibrillar structures, we determined the effect of heme on αSyn oligomerization by several different techniques, including native (nondenaturing) polyacrylamide gel electrophoresis, thioflavin T fluorescence, transmission electron microscopy, atomic force microscopy, circular dichroism, and membrane permeation using a calcein release assay. During aggregation, heme is able to bind the αSyn in a specific fashion, stabilizing distinct oligomeric conformations and promoting the formation of αSyn into annular structures, thereby delaying and/or inhibiting the fibrillation process. These results indicate that heme may play a regulatory role in the progression of Parkinson's disease; in addition, they provide insights into how the aggregation process may be altered, which may be applicable to the understanding of many neurodegenerative diseases.

Safety of Percutaneous Ultrasound-Guided Kidney Biopsy in Patients with AA Amyloidosis

BACKGROUND

Bleeding is the most frequent complication of kidney biopsy. Although bleeding risk in patients with AA amyloidosis after kidney biopsy has not been studied in a large population, AA amyloidosis has long been perceived as a risk factor for bleeding. The aim of the present study was to evaluate post-biopsy bleeding risk in patients with AA amyloidosis.

METHODS

We retrospectively analyzed bleeding complications in 88 patients with AA amyloidosis and 202 controls after percutaneous kidney biopsy. All the kidney biopsies were performed under the guidance of real-time ultrasound with the use of an automated core biopsy system after a standard pre-biopsy screening protocol. Bleeding events were classified as major when transfusion of blood products or surgical or radiological intervention was required, or if the bleeding caused hypovolemic shock or death. Bleeding events that did not meet these criteria were accepted as minor.

RESULTS

The incidence of post-biopsy bleeding was comparable between AA amyloidosis and control groups (5.7 vs. 5.0%, p = 0.796). Major bleeding events were observed in 3 patients from each group (p = 0.372). Selective renal angiography and embolization were applied to 2 patients from the AA amyloidosis group. One of these patients underwent colectomy and died because of infectious complications. Bleeding events were minor in 2.3% of the patients with AA amyloidosis and 3.5% of the controls (p = 0.728).

CONCLUSIONS

AA amyloidosis was not associated with increased post-biopsy bleeding risk. Kidney biopsy is safe in AA amyloidosis when standard pre-biopsy screening is applied. Further data are needed to confirm these findings.

Unknown aspect of the old disease: does dyslipidemia in systemic AA amyloidosis differ from the dyslipidemia in primary glomerulonephritis?

AIM

To investigate the nature of dyslipidemia and its diversity in patients with systemic AA amyloidosis.

METHODS

The reports of the kidney biopsies performed due to nephrotic proteinuria (>3.5 g/day/1.73 m(2)) with preserved renal function [glomerular filtration rate (GFR) >60 mL/min/1.73 m(2)] were reviewed. Clinical and laboratory data of the patients with systemic AA amyloidosis and primary glomerulonephritis (PG) were analyzed.

RESULTS

A total of 104 (systemic AA amyloidosis: 43, PG: 61) patients were included in the study. Proteinuria and GFR levels were similar in both the groups. Patients with systemic AA amyloidosis group had lower serum albumin (p = 0.002), lower hemoglobin levels (p = 0.001), higher platelet counts (p = 0.002) and higher C-reactive protein levels (p = 0.001) compared to patients in PG group. Although the frequency of dyslipidemia was similar in the groups (86.0 vs. 93.4%), patients with systemic amyloidosis had both lower values of LDL-C (4.56 ± 2.05 vs. 5.49 ± 2.23 mmol/L, p = 0.028) and HDL-C (1.19 ± 0.36 vs. 1.35 ± 0.39 mmol/L, p = 0.035). Serum lipid levels were correlated with serum total protein, albumin and proteinuria levels in PG group. However, in the systemic amyloidosis group, only one clear correlation between serum lipid and hemoglobin levels was estimated. A multivariate analysis demonstrated that LDL-C was independently associated with the etiology of nephrotic proteinuria, serum total protein, serum albumin (inversely) and hemoglobin levels.

CONCLUSIONS

Although dyslipidemia is closely associated with serum total protein, albumin and proteinuria in patients with PG, there is no clear such association in patients with systemic amyloidosis. Correlation between serum lipid and hemoglobin levels in this group and other findings point out that probably complex mechanisms take place in dyslipidemia of nephrotic syndrome caused by systemic AA amyloidosis.

Amyloid biomarkers in Alzheimer's disease

Aggregation of amyloid-β (Aβ) into oligomers, fibrils, and plaques is central in the molecular pathogenesis of Alzheimer's disease (AD), and is the main focus of AD drug development. Biomarkers to monitor Aβ metabolism and aggregation directly in patients are important for further detailed study of the involvement of Aβ in disease pathogenesis and to monitor the biochemical effect of drugs targeting Aβ in clinical trials. Furthermore, if anti-Aβ disease-modifying drugs prove to be effective clinically, amyloid biomarkers will be of special value in the clinic to identify patients with brain amyloid deposition at risk for progression to AD dementia, to enable initiation of treatment before neurodegeneration is too severe, and to monitor drug effects on Aβ metabolism or pathology to guide dosage. Two types of amyloid biomarker have been developed: Aβ-binding ligands for use in positron emission tomography (PET) and assays to measure Aβ42 in cerebrospinal fluid (CSF). In this review, we present the rationales behind these biomarkers and compare their ability to measure Aβ plaque load in the brain. We also review possible shortcomings and the need of standardization of both biomarkers, as well as their implementation in the clinic.

Hydrogen sulfide inhibits amyloid formation

Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and vascular dementia. The amount of hydrogen sulfide (H₂S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer’s disease relative to that of healthy individuals. These findings prompted us to investigate the effects of H₂S on the formation of amyloids in vitro using a model fibrillogenic protein hen egg white lysozyme (HEWL). HEWL forms typical β-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H₂S completely inhibits the formation of β-sheet and amyloid fibrils, as revealed by deep UV resonance Raman (DUVRR) spectroscopy and ThT fluorescence. Nonresonance Raman spectroscopy shows that disulfide bonds undergo significant rearrangements in the presence of H₂S. Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550–500 cm^–1 spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm^–1 band assigned to the trisulfide group (RSSSR) based on the comparison with model compounds. The formation of RSSSR was proven further using a reaction with TCEP reduction agent and LC-MS analysis of the products. Intrinsic tryptophan fluorescence study shows a strong denaturation of HEWL containing trisulfide bonds. The presented evidence indicates that H₂S causes the formation of trisulfide bridges, which destabilizes HEWL structure, preventing protein fibrillation. As a result, small spherical aggregates of unordered protein form, which exhibit no cytotoxicity by contrast with HEWL fibrils.

Recent progress in the understanding and treatment of transthyretin amyloidosis

WHAT IS KNOWN AND OBJECTIVE

Transthyretin (TTR) is a representative amyloidogenic protein in humans. Rate-limiting tetramer dissociation and rapid monomer misfolding and misassembly of variant TTR result in autosomal dominant familial amyloidosis. Analogous misfolding of wild-type TTR results in senile systemic amyloidosis (SSA) presenting as sporadic amyloid disease in the elderly. The objective of this review is to summarize recent progress in our understanding and treatment of TTR amyloidosis.

METHODS

Literature searches were conducted on the topics of transthyretin, familial amyloid polyneuropathy and clinical trials, using PubMed, the United States clinical trials directory, pharmaceutical company websites and news reports. The information was collected, evaluated for relevance and quality, critically assessed and summarized.

RESULTS AND DISCUSSION

The current standard first-line treatment of familial TTR amyloidosis is liver transplantation. However, large numbers of patients are not suitable transplant candidates. Recently, the clinical effects of TTR tetramer stabilizers, tafamidis and diflunisal, were demonstrated in randomized clinical trials, and tafamidis has been approved for the treatment of FAP in European countries and Japan. In addition, gene therapies with antisense oligonucleotides and small interfering RNAs are promising strategies to ameliorate TTR amyloidoses and are currently in clinical trials.

WHAT IS NEW AND CONCLUSIONS

Liver transplantation to treat the familial TTR amyloidosis will likely be replaced by other less invasive therapies, such as TTR tetramer stabilizers and possibly gene therapy approaches. These newly developed therapies are expected to be effective for not only familial TTR amyloidosis but also SSA, based on their mechanisms of action.