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

Primary localized cutaneous lichen myxedematosus with light chain-restricted plasma cells: A distinct variant of the localized form of lichen myxedematosus

Lichen myxedematosus (LM) is a chronic cutaneous mucinosis that can present as a localized skin lesion or as a generalized systemic disease termed scleromyxedema. The differential diagnosis is determined by a combination of clinical presentation, serological studies, and histopathological examination. Currently, well-established and accepted histopathological features to distinguish localized LM from scleromyxedema have not been elucidated. Our recent publication, together with a retrospective literature review, suggests that the presence of groups of light chain-restricted plasma cells represents a distinct histopathological clue for the diagnosis of localized LM. In this report, we provide two additional cases of localized LM with lambda light chain-restricted plasma cells, together with clinical and histopathological findings that are similar to our previous publication. These cases support our theory that the light chain-restricted plasmacytic microenvironment is primarily attributed to the pathogenesis of localized LM. Therefore, we consider these cases to constitute a clinically and pathologically new variant of localized LM and name it primary localized cutaneous LM with light chain-restricted plasma cells.

The advent of Alzheimer treatments will change the trajectory of human aging

Slowing neurodegenerative disorders of late life has lagged behind progress on other chronic diseases. But advances in two areas, biochemical pathology and human genetics, have now identified early pathogenic events, enabling molecular hypotheses and disease-modifying treatments. A salient example is the discovery that antibodies to amyloid ß-protein, long debated as a causative factor in Alzheimer's disease (AD), clear amyloid plaques, decrease levels of abnormal tau proteins and slow cognitive decline. Approval of amyloid antibodies as the first disease-modifying treatments means a gradually rising fraction of the world's estimated 60 million people with symptomatic disease may decline less or even stabilize. Society is entering an era in which the unchecked devastation of AD is no longer inevitable. This Perspective considers the impact of slowing AD and other neurodegenerative disorders on the trajectory of aging, allowing people to survive into late life with less functional decline. The implications of this moment for medicine and society are profound.

Aβ Amyloid Scaffolds the Accumulation of Matrisome and Additional Proteins in Alzheimer's Disease

We report a highly significant correlation in brain proteome changes between Alzheimers disease (AD) and CRND8 APP695NL/F transgenic mice. However, integrating protein changes observed in the CRND8 mice with co-expression networks derived from human AD, reveals both conserved and divergent module changes. For the most highly conserved module (M42, matrisome) we find many proteins accumulate in plaques, cerebrovascular amyloid (CAA), dystrophic processes, or a combination thereof. Overexpression of two M42 proteins, midkine (Mdk) and pleiotrophin (PTN), in CRND8 mice brains leads to increased accumulation of A β ; in plaques and in CAA; further, recombinant MDK and PTN enhance A β ; aggregation into amyloid. Multiple M42 proteins, annotated as heparan sulfate binding proteins, bind to fibrillar A β 42 and a non-human amyloid fibril in vitro. Supporting this binding data, MDK and PTN co-accumulate with transthyretin (TTR) amyloid in the heart and islet amyloid polypeptide (IAPP) amyloid in the pancreas. Our findings establish several critical insights. Proteomic changes in modules observed in human AD brains define an A β ; amyloid responsome that is well conserved from mouse model to human. Further, distinct amyloid structures may serve as scaffolds, facilitating the co-accumulation of proteins with signaling functions. We hypothesize that this co-accumulation may contribute to downstream pathological sequalae. Overall, this contextualized understanding of proteomic changes and their interplay with amyloid deposition provides valuable insights into the complexity of AD pathogenesis and potential biomarkers and therapeutic targets.

Diagnostic and Treatment Strategies for AL Amyloidosis in an Era of Therapeutic Innovation

Despite significant progress and improving outcomes in the management of plasma cell disorders, AL amyloidosis remains diagnostically and therapeutically challenging for clinicians across practice settings. There is, however, a reason for optimism with the advent of new combination therapy approaches and novel targets offering the promise of improvement in end organ function, survival, and quality of life. This review offers a clinically applicable overview of an approach to diagnosis, risk stratification, and clinical management of AL amyloidosis in an era of rapid therapeutic innovation.

Bladder triangle amyloidosis: A case report and literature review

RATIONALE

Amyloidosis is a group of benign lesions characterized by extracellular deposition of amyloid proteins. Amyloidosis lesions can occur in various organs of the body, but rarely in the urinary system. Amyloidosis in the bladder trigone is extremely rare.

PATIENT CONCERNS

An 80-year-old female patient presented with painless whole-course gross hematuria with reddish urine and no blood clots, accompanied by right lumbar discomfort.

DIAGNOSIS

Based on the patient's medical history and cystoscopy findings, the relevant literature was reviewed and a preoperative diagnosis of bladder tumor was made, although bladder amyloidosis was not excluded. Postoperative pathology ultimately revealed bladder amyloidosis.

INTERVENTIONS

The patient underwent resection of bladder tumor and ureteral stent implantation. Postoperatively, the patient was maintained on antibiotics and oral colchicine treatment.

OUTCOMES

Two months after surgery the patient reported that the gross hematuria had disappeared, and that the right lumbar discomfort was significantly relieved.Cystoscopy showed no obvious recurrence in the operative area, but magnetic resonance imaging (MRI) suggested recurrence. The patient refused partial cystectomy, and the ureteral stent was removed.

LESSON

The clinical manifestations of bladder amyloidosis are nonspecific, and under cystoscopy can be easily confused with bladder tumors. Accurate diagnosis of bladder amyloidosis relies on histopathology. Transurethral resection of bladder tumors or partial cystectomy is an option for surgical treatment; the latter should be performed if the ureteral opening is involved.

Localized light chain amyloidosis: A self-limited plasmacytic B-cell lymphoproliferative disorder

Immunoglobulin light chain amyloidosis can be either systemic or localized. Although these conditions share a similar name, they are strikingly different. Localized light chain amyloidosis has been challenging to characterize due to its lower incidence and highly heterogeneous clinical presentation. Here, we review the emerging literature, emphasizing recent reports on large cohorts of patients with localized amyloidosis, and provide insights into this condition's pathology and natural history. We find that patients with localized amyloidosis have an excellent prognosis with overall survival similar to that of the general population. Furthermore, the risk of progression to systemic disease is low and likely represents initial mischaracterization as localized disease. Therefore, we argue for the incorporation of more sensitive techniques to rule out systemic disease at diagnosis. Despite increasing mechanistic understanding of this condition, much remains to be discovered regarding the cellular clonal evolution and the molecular processes that give rise to localized amyloid formation. While localized surgical resection of symptomatic disease is typically the treatment of choice, the presentation of this disease across the spectrum of plasmacytic B-cell lymphoproliferative disorders, and the frequent lack of an identifiable neoplastic clone, can make therapy selection a challenge in the uncommon situation that systemic chemotherapy is required.

Ultrasensitive Detection of C-Reactive Protein by a Novel Nanoplasmonic Immunoturbidimetry Assay

Nanotechnology has attracted much attention, and may become the key to a whole new world in the fields of food, agriculture, building materials, machinery, medicine, and electrical engineering, because of its unique physical and chemical properties, including high surface area and outstanding electrical and optical properties. The bottom-up approach in nanofabrication involves the growth of particles, and we were inspired to propose a novel nanoplasmonic method to detect the formation of nanoparticles in real time. This innovative idea may contribute to the promotion of nanotechnology development. An increase in nanometer particle size leads to optical extinction or density (OD)-value changes in our nanosensor chip at a specific wavelength measured in a generic microplate reader. Moreover, in applying this method, an ultrasensitive nanoplasmonic immunoturbidimetry assay (NanoPITA) was carried out for the high-throughput quantification of hypersensitive C-reactive protein (CRP), a well-known biomarker of cardiovascular, inflammatory, and tumor diseases. The one-step detection of the CRP concentration was completed in 10 min with high fidelity, using the endpoint analysis method. The new NanoPITA method not only produced a linear range from 1 ng/mL to 500 ng/mL CRP with the detection limit reduced to 0.54 ng/mL, which was an improvement of over 1000 times, with respect to regular immunoturbidity measurement, but was also effective in blood detection. This attractive method, combined with surface plasmon resonance and immunoturbidimetry, may become a new technology platform in the application of biological detection.

Noninvasive Diagnostics of Renal Amyloidosis: Current State and Perspectives

Amyloidoses is a group of diseases characterized by the accumulation of abnormal proteins (called amyloids) in different organs and tissues. For systemic amyloidoses, the disease is related to increased levels and/or abnormal synthesis of certain proteins in the organism due to pathological processes, e.g., monoclonal gammopathy and chronic inflammation in rheumatic arthritis. Treatment of amyloidoses is focused on reducing amyloidogenic protein production and inhibition of its aggregation. Therapeutic approaches critically depend on the type of amyloidosis, which underlines the importance of early differential diagnostics. In fact, the most accurate diagnostics of amyloidosis and its type requires analysis of a biopsy specimen from the disease-affected organ. However, absence of specific symptoms of amyloidosis and the invasive nature of biomaterial sampling causes the late diagnostics of these diseases, which leads to a delayed treatment, and significantly reduces its efficacy and patient survival. The establishment of noninvasive diagnostic methods and discovery of specific amyloidosis markers are essential for disease detection and identification of its type at earlier stages, which enables timely and targeted treatment. This review focuses on current approaches to the diagnostics of amyloidoses, primarily with renal involvement, and research perspectives in order to design new specific tests for early diagnosis.

Removal of cardiac AL amyloid with positive remodelling of cardiomyocytes and of restrictive cardiomyopathy

Herein, we describe histological mobilization of light chain cardiac amyloid documented by sequential left ventricular endomyocardial biopsies. These findings were associated with positive remodelling of cardiomyocytes and of restrictive cardiomyopathy resulting from 14 courses of chemotherapy over 17 years of time. Histological and ultrastructural findings of light chain cardiac amyloid removal led to increase in cardiomyocyte dimension and electrocardiogram voltages, reduction of biventricular wall thickness with improvement of left ventricular diastolic function, and NYHA class shifting from III to I.

Site-Directed Chemical Modification of Amyloid by Polyoxometalates for Inhibition of Protein Misfolding and Aggregation

Post-translational modification (PTM) of protein can significantly change protein conformation and function. Inspired by the natural PTM, we present a new approach to inhibit amyloid aggregation by chemical PTM modification. Polyoxometalates (POMs) were used as examples of inhibitors of β-amyloid peptide (Aβ) aggregation to illustrate the chemical PTM method. After the POMs were modified with thiazolidinethione (TZ), the resulting POMD-TZ acted as a chemical PTM agent and could covalently modify Aβ site-selectively at Lys16. Multiple biophysical techniques and biochemical assays have been employed to show the superiority of the chemical PTM method compared to traditional Aβ inhibitors. Since Aβ oligomers are more cytotoxic, we further functionalized POMD-TZ with an Aβ-targeted peptide and a fluorescent probe to obtain an "Aβ oligomer sensitive" probe. The use of PTM agents for the site-directed chemical modification of proteins provides a new way to regulate amyloid aggregation.

Cutaneous manifestations of monoclonal gammopathy

Monoclonal gammopathy associated with dermatological manifestations are a well-recognized complication. These skin disorders can be associated with infiltration and proliferation of a malignant plasma cells or by a deposition of the monoclonal immunoglobulin in a nonmalignant monoclonal gammopathy. These disorders include POEMS syndrome, light chain amyloidosis, Schnitzler syndrome, scleromyxedema and TEMPI syndrome. This article provides a review of clinical manifestations, diagnostics criteria, natural evolution, pathogenesis, and treatment of these cutaneous manifestations.

Fibulin-4 accelerates amyloid formation through binding with a keratin 5 peptide fragment

Keratins are the major amyloid fibril component in localized cutaneous amyloidosis. We analyzed the amyloid components in the skin of patients with localized cutaneous amyloidosis by immunohistochemical staining using antisera against extracellular matrix proteins and keratin 5 (K5). Fibulin-4 and K5 colocalized in the amyloid deposits. Using 14 synthetic peptides, we screened for amyloidogenic sequences in the C-terminal region of K5, including the α-helical rod domain and the tail domain. Two peptides stained with thioflavin T possessed a β-sheet structure and formed amyloid-like fibrils. Among the amyloidogenic peptides, a peptide KT5-6 (YQELMNTKLALDVEIATYRKLLEGE) derived from the α-helical rod domain of K5 specifically bound to fibulin-4. In addition, amyloid formation of KT5-6 was accelerated by fibulin-4. These results suggest that degraded fragments of K5 containing the KT5-6 sequence form amyloid fibrils with fibulin-4. The data further suggest that degraded fragments of K5 and fibulin-4 have the potential to initiate cutaneous amyloidosis.

1H detection and dynamic nuclear polarization-enhanced NMR of Aβ1-42 fibrils

Amyloid-β (Aβ) is the subject of intense scrutiny because of its close association with Alzheimer’s disease (AD), which currently afflicts about 50 million people worldwide. The results reported in this manuscript focus on the new possibilities provided by ultrafast magic-angle spinning (MAS) ¹H detection and fast-MAS dynamic nuclear polarization (DNP), which have ushered in a new era for NMR-based structural biology, but whose potential has not yet been fully exploited for the structural investigation of complex amyloid assemblies. This work demonstrates the expeditious structural analysis of amyloid fibrils, without requiring preparation of large sample amounts, and sets the stage for future studies of unlabeled AD peptides derived from tissue samples available in limited quantities.

Several publications describing high-resolution structures of amyloid-β (Aβ) and other fibrils have demonstrated that magic-angle spinning (MAS) NMR spectroscopy is an ideal tool for studying amyloids at atomic resolution. Nonetheless, MAS NMR suffers from low sensitivity, requiring relatively large amounts of samples and extensive signal acquisition periods, which in turn limits the questions that can be addressed by atomic-level spectroscopic studies. Here, we show that these drawbacks are removed by utilizing two relatively recent additions to the repertoire of MAS NMR experiments—namely, ¹H detection and dynamic nuclear polarization (DNP). We show resolved and sensitive two-dimensional (2D) and three-dimensional (3D) correlations obtained on ¹³C,¹⁵N-enriched, and fully protonated samples of M₀Aβ_1-42 fibrils by high-field ¹H-detected NMR at 23.4 T and 18.8 T, and ¹³C-detected DNP MAS NMR at 18.8 T. These spectra enable nearly complete resonance assignment of the core of M₀Aβ_1-42 (K16-A42) using submilligram sample quantities, as well as the detection of numerous unambiguous internuclear proximities defining both the structure of the core and the arrangement of the different monomers. An estimate of the sensitivity of the two approaches indicates that the DNP experiments are currently ∼6.5 times more sensitive than ¹H detection. These results suggest that ¹H detection and DNP may be the spectroscopic approaches of choice for future studies of Aβ and other amyloid systems.

Light Chain Stabilization: A Therapeutic Approach to Ameliorate AL Amyloidosis

Non-native immunoglobulin light chain conformations, including aggregates, appear to cause light chain amyloidosis pathology. Despite significant progress in pharmacological eradication of the neoplastic plasma cells that secrete these light chains, in many patients impaired organ function remains. The impairment is apparently due to a subset of resistant plasma cells that continue to secrete misfolding-prone light chains. These light chains are susceptible to the proteolytic cleavage that may enable light chain aggregation. We propose that small molecules that preferentially bind to the natively folded state of full-length light chains could act as pharmacological kinetic stabilizers, protecting light chains against unfolding, proteolysis and aggregation. Although the sequence of the pathological light chain is unique to each patient, fortunately light chains have highly conserved residues that form binding sites for small molecule kinetic stabilizers. We envision that such stabilizers could complement existing and emerging therapies to benefit light chain amyloidosis patients.

Shear wave elastography evaluation of liver, pancreas, spleen and kidneys in patients with familial mediterranean fever and amyloidosis

OBJECTIVES

Amyloid deposits in a visceral organ can contribute to tissue stiffness that could be measured with shear wave elastography (SWE). We aimed to investigate changes in organ stiffness in conjunction with laboratory parameters in patients with Familial Mediterranean Fever (FMF) and amyloidosis.

METHODS

This prospective study included 27 FMF patients, 11 patients with amyloidosis, and 38 healthy controls. Median shear wave elasticity values of the liver, spleen, both kidneys, and pancreas on SWE were compared among study and control groups. The mean values of CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) were compared by the t-test and the median of SAA (serum amyloid A protein) was compared with the Mann-Whitney U test between FMF groups with and without amyloidosis. Spearman's correlation analysis was performed to reveal the association between stiffness values and laboratory parameters.

RESULTS

The median liver, spleen, kidney, and pancreas elasticity values were significantly higher in the FMF group with amyloidosis compared to control subjects. The median kidney stiffness values in the FMF group with or without amyloidosis were significantly higher compared to control subjects. Median liver stiffness values in FMF patients with amyloidosis were significantly higher than FMF patients without amyloidosis. There were statistically significant positive correlations between the CRP (p = 0.001, r = 0.56), ESR (p = 0.001, r = 0.61), and SAA (p = 0.002, r = 0.53) levels with spleen stiffness, and CRP (p = 0.006, r = 0.48) and ESR (p = 0.001,r = 0.61) levels with pancreas stiffness, and ESR (p = 0.004, r = 0.51) levels with the left kidney stiffness.

CONCLUSION

SWE could be a potential tool for noninvasive follow-up of FMF patients and also amyloid deposition.

ADVANCES IN KNOWLEDGE

Both acute inflammation and amyloidosis in the FMF patients could increase organ stiffness.

Mass spectrometry-based proteomic analysis of parathyroid adenomas reveals PTH as a new human hormone-derived amyloid fibril protein

BACKGROUND

Congo red-positive material was described in normal and diseased parathyroids (adenoma and hyperplasia) 50 years ago. However, the incidence and the clinical significance of such observation are unknown, and the causal fibril protein has never been convincingly demonstrated.

METHODS

We conducted the present study including an exceptional case report accompanied with a retrospective study of 105 parathyroid adenomas. We used histopathological, immunohistochemical, ultrastructural, mass spectrometry-based proteomic analysis of parathyroid adenoma tissue samples, and genetic analysis.

RESULTS

We describe a 57-year-old man with mild hypercalcemia and elevated parathyroid hormone (PTH) level for whom histopathological analysis revealed a parathyroid adenoma associated with nodular typical amyloid deposits. Tandem mass spectrometry after laser microdissection (LMD-MS) of amyloid adenoma identified PTH as the fibril protein, and no germline mutation in the PTH gene was detected. Congo red-positive PTH-deposits were further observed in 6.6% of the parathyroid adenomas analyzed, and were associated with complete/incomplete or absent universal amyloid signature, but with fibrillar morphology at ultrastructural level.

CONCLUSIONS

Inappropriate PTH production leads to progressive disease-amyloid aggregation of PTH in a subset of parathyroid adenomas, providing new insights into the pathophysiology of this condition and adding PTH to the list of amyloid protein derived from hormones.

Early-stage culprit in protein misfolding diseases investigated using electrochemical parameters: New insights over peptide-membrane interactions

The dysfunctioning of β-cells caused by the unspecific misfolding of the human islet amyloid polypeptide (hIAPP) at the membrane results in type 2 diabetes mellitus. Here, we report for the first time, the early-stage interaction of hIAPP oligomers on the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) lipid membrane using electrochemical parameters. Electrochemical techniques are better than other techniques to detect hIAPP at significantly lower concentrations. The surface level interactions between the peptide (hIAPP) and lipid membrane (DMPC) were investigated using atomic force microscopy (AFM), confocal microscopy (CM) and electrochemical techniques such as Tafel polarization, cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Inserting IAPP into the fluid domains results in breaking the lipid-to-lipid interaction, leading to restriction of membrane mobility. The S_Lateral values of the liposome and IAPP co-solubilized liposome indicates the cooperative insertion of IAPP. Further, a new method of immobilizing a membrane to the gold surface has been employed, resulting in an electrical contact with the buffer, preventing the direct utilization of a steady-state voltage across the bilayer. The electrochemical studies revealed that the charge transfer resistance decreased for 3-mercaptopropanoic acid modified gold (MPA-Au) electrode coated with the liposome and after the addition of IAPP, followed by an increase in the capacitance. The present study has opened up new dimensions to the understanding of peptide-membrane interactions and shows different experimental approaches for the future researchers in this domain.

Liquid-liquid crystalline phase separation in biological filamentous colloids: nucleation, growth and order-order transitions of cholesteric tactoids

The process of liquid-liquid crystalline phase separation (LLCPS) in filamentous colloids is at the very core of multiple biological, physical and technological processes of broad significance. However, the complete theoretical understanding of the process is still missing. LLCPS involves the nucleation, growth and up-concentration of anisotropic droplets from a continuous isotropic phase, until a state of equilibrium is reached. Herein, by combining the thermodynamic extremum principle with the Onsager theory, we describe the nucleation and growth of liquid crystalline droplets, and the evolution of their size and concentration during phase separation, eventually leading to a multitude of order-order phase transitions. Furthermore, a decreasing pitch behaviour can be predicted using this combined theory during tactoid growth, already observed experimentally but not yet explained by present theories. The results of this study are compared with the experimental data of cholesteric pitch, observed in three different systems of biological chiral liquid crystals. These findings give an important framework for predicting the formation, growth and phase behaviour of biological filamentous colloids undergoing LLCPS, advancing our understanding of liquid-liquid phase separation and self-assembly mechanisms in biological systems, and provide a valuable rationale for developing nanomaterials and applications in nanotechnology.

Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis with Kidney Involvement in a Patient with AL Amyloidosis

Antineutrophil cytoplasmic autoantibody (ANCA) vasculitis has occasionally been associated with other systemic glomerulonephritis, such as anti-glomerular basement membrane disease. Here, we report the first clinical case of ANCA-associated crescentic glomerulonephritis with AL amyloidosis. An 81-years-old gentleman presented to the hospital with acute kidney injury (serum creatinine 4.7 mg/dL) on a background of chronic kidney disease and volume overload. Autoimmune serology was remarkable for p-ANCA and myeloperoxidase positivity. A renal biopsy confirmed pauci-immune glomerulonephritis and lambda light-chain amyloid deposition (confirmed on liquid chromatography and tandem mass spectrometry). The patient was initially managed with rituximab and subsequently transitioned to bortezomib-based chemotherapy but died due to decompensated heart failure. This case report promotes greater awareness of the unusual presentation of amyloidosis and guides future research and treatment.

Autopsy findings in a patient with primary systemic AL (kappa light chain) amyloidosis

First described by Rokitansky in 1842, and further characterized by Virchow in 1854, amyloidosis is a disorder caused by amyloid deposition, a fibrillary insoluble protein. The clinical spectrum of amyloidosis is broad, as the amyloid deposition may virtually occur in all tissues. Herein, we report the case of a 66-year-old man with a long-lasting emaciating disease, diagnosed, at autopsy, with primary systemic amyloidosis. Amyloid protein deposition was found in many tissues and organs. The involvement of the vessels’ wall rendered ischemic injury most prominent in the intestinal loops causing mesenteric ischemia. Despite the thorough organic involvement, the immediate cause of death was aspiration bronchopneumonia. Massive amyloid deposition was found in virtually all major organs, such as the heart, liver, kidneys, spleen, pancreas, adrenals, prostate, skin, and thyroid: the latter, a complication of the amyloidosis known as amyloid goiter. Post-mortem review of the deceased’s laboratory workup showed a slightly abnormal kappa:lambda ratio in the blood; however, no clonal lymphoplasmacytic disorder was confirmed in the bone marrow and other lymphoreticular system organs either by the microscopic examination and immunohistochemical staining. Laser-capture microdissection and tandem mass spectrometry of the splenic tissue detected a peptide profile consistent with an immunoglobulin Kappa light chain. The presence of amyloid purpura favors the diagnosis of primary systemic amyloidosis.

Proteomic analysis shows that the main constituent of subepidermal localised cutaneous amyloidosis is not galectin-7

Lichen or macular localised cutaneous amyloidoses have long been described as keratinic amyloidoses and believed to be due to the deposition of cytokeratin peptides originating from epidermis in the dermal papillae. However, recently it was suggested that galectin-7 is the causative protein for this type of amyloidosis. This was based on the detection of galectin-7 in a biopsy from a patient diagnosed with Bowen's disease and localised cutaneous amyloidosis. In this study we report mass spectrometry-based proteomic analysis of the protein composition of localised cutaneous amyloid deposits from seven patients using laser microdissection and show that basal keratins are the main constituents of the amyloid deposits. Galectin-7 was not present in the dermal amyloid deposits and was only present in the overlying Congo red negative epidermis.

Amyloid cranial polyneuropathy: A rare neurological presentation of immunoglobulin light-chain amyloidosis

Amyloidosis, a disease with extracellular tissue deposition of fibrils, results in clinical manifestations based on deposition of these fibrils in multiple organ systems. Usual manifestations include nephrotic-range proteinuria, cardiac failure, hepatosplenomegaly, and skin manifestations. Common neurological manifestations include peripheral and autonomic neuropathies. Cranial neuropathy has been seldom reported and is an unusual clinical feature of amyloidosis. Here, we report an older man who presented with cranial nerve palsies along with other clinical features, including heart failure, proteinuria, weight loss, anorexia and distal symmetric polyneuropathy and was diagnosed with immunoglobulin light-chain (AL) amyloidosis.

Investigating an increase in Florida manatee mortalities using a proteomic approach

Two large-scale Florida manatee (Trichechus manatus latirostris) mortality episodes were reported on separate coasts of Florida in 2013. The east coast mortality episode was associated with an unknown etiology in the Indian River Lagoon (IRL). The west coast mortality episode was attributed to a persistent Karenia brevis algal bloom or 'red tide' centered in Southwest Florida. Manatees from the IRL also had signs of cold stress. To investigate these two mortality episodes, two proteomic experiments were performed, using two-dimensional difference in gel electrophoresis (2D-DIGE) and isobaric tags for relative and absolute quantification (iTRAQ) LC-MS/MS. Manatees from the IRL displayed increased levels of several proteins in their serum samples compared to controls, including kininogen-1 isoform 1, alpha-1-microglobulin/bikunen precursor, histidine-rich glycoprotein, properdin, and complement C4-A isoform 1. In the red tide group, the following proteins were increased: ceruloplasmin, pyruvate kinase isozymes M1/M2 isoform 3, angiotensinogen, complement C4-A isoform 1, and complement C3. These proteins are associated with acute-phase response, amyloid formation and accumulation, copper and iron homeostasis, the complement cascade pathway, and other important cellular functions. The increased level of complement C4 protein observed in the red tide group was confirmed through the use of Western Blot.

AL amyloidosis presenting as inflammatory polyarthritis: a case report

Amyloidosis is a condition characterised by extracellular tissue deposition of fibrils causing a wide range of clinical manifestations. This protein deposition can occur in any tissue, most commonly in the kidney, heart, skin, peripheral nervous system, and gastrointestinal tract. However, the deposition of amyloid fibrils in the synovium is seldom reported. Musculoskeletal manifestations are subtle, subclinical and rarely the patient presents with symptoms that resemble rheumatic diseases. Here, we describe a 55-year-old man with AL (amyloid light chain) amyloidosis who presented with inflammatory polyarthritis with significant morning stiffness, inflammatory low back pain, and painful thickened tongue. The patient had anaemia, macroglossia with lateral scalloping of the tongue, papules, and plaques in the periocular, perioral and perinasal area, bilateral carpal tunnel syndrome, localised soft tissue swelling over the joints, restricted movement in different joints with flexion contractures in some joints. Rheumatoid factor and ACPA were negative and the X-ray of the sacroiliac joints was normal. We confirmed amyloidosis by biopsy of an affected skin lesion. In the urine, no Bence Jones protein was found and bone marrow study and x-ray of the skull were normal. Plasma immuno-electrophoresis and serum free light chain (FLC) assay confirmed lambda light chain type monoclonal gammopathy. Take home message: Although AL amyloidosis is a rare condition, it should be considered while evaluating atypical symptoms in patients presenting with rheumatic complaints. A high index of suspicion is necessary for proper diagnosis as delay in diagnosis will yield a poorer treatment outcome.

Thioflavin-positive tau aggregates complicating quantification of amyloid plaques in the brain of 5XFAD transgenic mouse model

Transgenic mouse models recapitulating Alzheimer's disease (AD) pathology are pivotal in molecular studies and drug evaluation. In transgenic models selectively expressing amyloid-β (Aβ), thioflavin S (ThS), a fluorescent dye with β-sheet binding properties, is widely employed to observe amyloid plaque accumulation. In this study, we investigated the possibility that a commonly used Aβ-expressing AD model mouse, 5XFAD, generates ThS-positive aggregates of β-sheet structures in addition to Aβ fibrils. To test this hypothesis, brain sections of male and female 5XFAD mice were double-stained with ThS and monoclonal antibodies against Aβ, tau, or α-synuclein, all of which aggregates are detected by ThS. Our results revealed that, in addition to amyloid plaques, 5XFAD mice express ThS-positive phospho-tau (p-tau) aggregates. Upon administration of a small molecule that exclusively disaggregates Aβ to 5XFAD mice for six weeks, we found that the reduction level of plaques was smaller in brain sections stained by ThS compared to an anti-Aβ antibody. Our findings implicate that the use of ThS complicates the quantification of amyloid plaques and the assessment of Aβ-targeting drugs in 5XFAD mice.

A rare case of amyloid light-chain amyloidosis with bilateral perirenal hematoma shortly after initiation of peritoneal dialysis

Peritoneal dialysis (PD) is valuable for patients starting on renal replacement therapy because it preserves residual renal function, maintains hemodynamic stability, and affords higher quality of life than hemodialysis. Amyloid-related kidney disease is a rare condition and a cause of end-stage renal disease, the incidence of which appears to be rising in recent years. Hemoperitoneum is a common complication of PD. In some cases, it requires urgent treatment and careful monitoring for deterioration and potential complications. Although the kidney is a retroperitoneal organ, renal hemorrhage can cause bloody peritoneal dialysate. We encountered a rare case of amyloid light-chain amyloidosis where bilateral perirenal hematoma occurred shortly after initiation of PD. Amyloid angiopathy with increased blood vessel fragility and impaired vasoconstriction may promote bleeding. Therefore, hemoperitoneum in a patient on PD with disease causing fragile blood vessels, such as amyloidosis, should alert the physician to the possibility of underlying angiopathy.

Amyloid-Like Peptide Aggregates

Self-assembly of proteins and peptides into the amyloid fold is a widespread phenomenon in the natural world. The structural hallmark of self-assembly into amyloid fibrillar assemblies is the cross-beta motif, which conveys distinct morphological and mechanical properties. The amyloid fibril formation has contrasting results depending on the organism, in the sense that it can bestow an organism with the advantages of mechanical strength and improved functionality or, on the contrary, could give rise to pathological states. In this chapter we review the existing information on amyloid-like peptide aggregates, which could either be derived from protein sequences, but also could be rationally or de novo designed in order to self-assemble into amyloid fibrils under physiological conditions. Moreover, the development of self-assembled fibrillar biomaterials that are tailored for the desired properties towards applications in biomedical or environmental areas is extensively analyzed. We also review computational studies predicting the amyloid propensity of the natural amino acid sequences and the structure of amyloids, as well as designing novel functional amyloid materials.

Amyloid β-protein and beyond: the path forward in Alzheimer's disease

Basic research on the biological mechanism of Alzheimer's disease has focused for decades on the age-related aggregation of the amyloid β-protein and its apparent downstream effects on microglia, astrocytes and neurons, including the posttranslational modification of the tau protein that seems necessary for symptom expression. Here, we discuss the highly challenging process of developing disease-modifying therapies and highlight several key areas of current research that are progressing in exciting directions. We conclude that further deep molecular analyses of the disease, including the mechanisms of β-amyloidosis, will enable more effective clinical trials and ultimately achieve the progress that our patients so deserve.

Structure and function of the perivascular fluid compartment and vertebral venous plexus: Illumining a novel theory on mechanisms underlying the pathogenesis of Alzheimer's, cerebral small vessel, and neurodegenerative diseases

Blood dynamically and richly supplies the cerebral tissue via microvessels invested in pia matter perforating the cerebral substance. Arteries penetrating the cerebral substance derive an investment from one or two successive layers of pia mater, luminally apposed to the pial-glial basal lamina of the microvasculature and abluminally apposed to a series of aquaporin IV-studded astrocytic end feet constituting the soi-disant glia limitans. The full investment of successive layers forms the variably continuous walls of the periarteriolar, pericapillary, and perivenular divisions of the perivascular fluid compartment. The pia matter disappears at the distal periarteriolar division of the perivascular fluid compartment. Plasma from arteriolar blood sequentially transudates into the periarteriolar division of the perivascular fluid compartment and subarachnoid cisterns in precession to trickling into the neural interstitium. Fluid from the neural interstitium successively propagates into the venules through the subarachnoid cisterns and perivenular division of the perivascular fluid compartment. Fluid fluent within the perivascular fluid compartment flows gegen the net direction of arteriovenular flow. Microvessel oscillations at the central tendency of the cerebral vasomotion generate corresponding oscillations of within the surrounding perivascular fluid compartment, interposed betwixt the abluminal surface of the vessels and internal surface of the pia mater. The precise microanatomy of this most fascinating among designable spaces has eluded the efforts of various investigators to interrogate its structure, though most authors non-consensusly concur the investing layers effectively and functionally segregate the perivascular and subarachnoid fluid compartments. Enlargement of the perivascular fluid compartment in a variety of neurological disorders, including senile dementia of the Alzheimer's type and cerebral small vessel disease, may alternately or coordinately constitute a correlative marker of disease severity and a possible cause implicated in the mechanistic pathogenesis of these conditions. Venular pressures modulating oscillatory dynamic flow within the perivascular fluid compartment may similarly contribute to the development of a variety among neurological disorders. An intimate understanding of subtle features typifying microanatomy and microphysiology of the investing structures and spaces of the cerebral microvasculature may powerfully inform mechanistic pathophysiology mediating a variety of neurovascular ischemic, neuroinfectious, neuroautoimmune, and neurodegenerative diseases.

Diagnosing cardiac amyloidosis in every-day practice: A practical guide for the cardiologist

Cardiac amyloidosis (CA) has emerged as a previously underestimated cause of heart failure and mortality. Underdiagnosis resulted mainly from unawareness of the true disease prevalence and the non-specific symptoms of the disease. CA results from extracellular deposition of misfolded protein fibrils, commonly derived from transthyretin (ATTR) or immunoglobulin light chains (AL). A significant proportion of older patients with heart failure and other extracardiac manifestations suffer from ATTR-CA, whereas AL-CA is still considered a rare disease. This article provides an overview of CA with a special focus on current and emerging diagnostic modalities. Furthermore, we provide a diagnostic algorithm for the evaluation of patients with suspected CA in every-day practice.

A Rare Nasopharyngeal Presentation of Amyloidosis

Amyloidosis is a heterogeneous group of diseases characterized by the extracellular deposition of insoluble proteins whose pathogenesis is not yet fully understood. The deposition of amyloid proteins can be systemic or localized, idiopathic or related to systemic diseases, mostly multiple myeloma or chronic inflammatory diseases. Localized head and neck amyloidosis is a rare entity, mainly involving the larynx. Given the rarity of the disease and the absence of a lasting follow-up protocol, there is no standard treatment defined for localized amyloidosis. We report a rare case of localized nasopharyngeal amyloidosis, treated with complete transoral resection and confirmed by histological examination.

Revisiting renal amyloidosis with clinicopathological characteristics, grading, and scoring: A single-institutional experience

INTRODUCTION:

Kidney involvement is a major cause of mortality in systemic amyloidosis. Glomerulus is the most common site of deposition in renal amyloidosis, and nephrotic syndrome is the most common presentation. Distinction between AA and AL is done using immunofluorescence (IF) and immunohistochemistry (IHC). Renal biopsy helps in diagnosis and also predicting the clinical course by applying scoring and grading to the biopsy findings.

MATERIALS AND METHODS:

The study includes all cases of biopsy-proven renal amyloidosis from January 2008 to May 2017. Light microscopic analysis; Congo red with polarization; IF; IHC for Amyloid A, kappa, and lambda; and bone marrow evaluation were done. Classification of glomerular amyloid deposition and scoring and grading are done as per the guidelines of Sen S et al.

RESULTS:

There are 40 cases of biopsy-proven renal amyloidosis with 12 primary and 23 secondary cases. Mean age at presentation was 42.5 years. Edema was the most common presenting feature. Secondary amyloidosis cases were predominant. Tuberculosis was the most common secondary cause. Multiple myeloma was detected in four primary cases. Grading of renal biopsy features showed a good correlation with the class of glomerular involvement.

CONCLUSION:

Clinical history, IF, and IHC are essential in amyloid typing. Grading helps provide a subtle guide regarding the severity of disease in the background of a wide range of morphological features and biochemical values. Typing of amyloid is also essential for choosing the appropriate treatment.

Fibrin(ogen) in human disease: both friend and foe

Fibrinogen is an abundant protein synthesized in the liver, present in human blood plasma at concentrations ranging from 1.5-4 g/L in healthy individuals with a normal half-life of 3-5 days. With fibrin, produced by thrombin-mediated cleavage, fibrinogen plays important roles in many physiological processes. Indeed, the formation of a stable blood clot, containing polymerized and cross-linked fibrin, is crucial to prevent blood loss and drive wound healing upon vascular injury. A balance between clotting, notably the conversion of fibrinogen to fibrin, and fibrinolysis, the proteolytic degradation of the fibrin mesh, is essential. Disruption of this equilibrium can cause disease in distinct manners. While some pathological conditions are the consequence of altered levels of fibrinogen, others are related to structural properties of the molecule. The source of fibrinogen expression and the localization of fibrin(ogen) protein also have clinical implications. Low levels of fibrinogen expression have been detected in extra-hepatic tissues, including carcinomas, potentially contributing to disease. Fibrin(ogen) deposits at aberrant sites including the central nervous system or kidney, can also be pathological. In this review, we discuss disorders in which fibrinogen and fibrin are implicated, highlighting mechanisms that may contribute to disease.

Neurodegenerative diseases as proteinopathies-driven immune disorders

In the pathophysiology of neurodegenerative disorders, the role of misfolded protein deposition leading to neurodegeneration has been primarily discussed. In the last decade, however, it has been proposed a parallel involvement of innate immune activation, chronic inflammation and adaptive immunity in the neurodegeneration mechanisms triggered by proteinopathies. New insights in the neurodegenerative field strongly suggest a role for the immune system in the pathophysiology of neurodegenerative disorders. Therefore, the hypothesis underlining the modulation of the innate and the adaptive immune system in the events linked to brain deposition of misfolded proteins could open new perspectives in the setting of specific immunotherapeutic strategies for the treatment of neurodegenerative diseases. Therefore, we have reviewed the pathogenic hypothesis in neurodegenerative pathologies, underling the links between the deposition of misfolded protein mechanisms and the immune activation.

Amyloidosis and Ocular Involvement: an Overview

Purpose: To describe the ophthalmic manifestations of amyloidosis and the corresponding therapeutic measures.Methods: The 178 patients included in the study had different types of amyloidosis, diagnosed at a single internal medicine institution (Bari, Italy). To provide a comprehensive review of the types of amyloidosis that can be associated with ocular involvement, the images and clinical descriptions of patients with amyloidosis structurally related to gelsolin, keratoepithelin and lactoferrin were obtained in collaborations with the ophthalmology departments of hospitals in Mainz (Germany) and Helsinki (Finland).Results: Overall, ocular morbidity was detected in 41 of the 178 patients with amyloidosis (23%). AL amyloidosis was diagnosed in 18 patients with systemic disease, 3 with multiple myeloma, and 11 with localized amyloidosis. AA amyloidosis was detected in 2 patients with rheumatoid arthritis and 3 with Behçet syndrome, and transthyretin amyloidosis in 4 patients. The treatment of AL amyloidosis is based on chemotherapy to suppress the production of amyloidogenic L-chains and on surgical excision of orbital or conjunctival masses. AA amyloidosis is managed by targeting the underlying condition. Vitreous opacities and additional findings of ocular involvement in patients with transthyretin amyloidosis indicate the need for pars plana vitrectomy. Gelsolin amyloidosis, characterized by lattice corneal amyloidosis and polyneuropathy, results in recurrent keratitis and corneal scarring, such that keratoplasty is inevitable. In patients with lattice corneal dystrophies associated with amyloid deposits of keratoepithelin fragments, corneal transparency is compromised by deposits of congophilic material in the subepithelial layer and deep corneal stroma. Patients with established corneal opacities are treated by corneal transplantation, but the prognosis is poor because recurrent corneal deposits are possible after surgery. In patients with gelatinous drop-like dystrophy, the amyloid fibrils that accumulate beneath the corneal epithelium consist of lactoferrin and can severely impair visual acuity. Keratoplasty and its variants are performed for visual rehabilitation.Conclusion: A routine ophthalmic follow-up is recommended for all patients with established or suspected amyloidosis, independent of the biochemical type of the amyloid. Close collaboration between the ophthalmologist and the internist will facilitate a more precise diagnosis of ocular involvement in amyloidosis and allow the multidisciplinary management of these patients.Abbreviations: CD: corneal dystrophy; CLA: corneal lattice amyloidosis; CNS: central nervous system; CT: computed tomography; FAP: familial amyloidotic polyneuropathy; GDLCD: gelatinous drop-like corneal dystrophy; GLN: gelsolin; LCD: lattice corneal dystrophy; MRI: magnetic resonance imaging; OLT: orthotopic liver transplantation; TEM: transmission electron microscopy; TGFBI: transforming growth factor β induced; TTR: transthyretin.

In familial Mediterranean fever, soluble TREM-1 plasma level is higher in case of amyloidosis

We aimed to explore triggering receptor expressed on myeloid cells-1 (TREM-1) activation in familial Mediterranean fever (FMF), the most frequent monogenic auto-inflammatory disease, through the measurement of its serum soluble form, named sTREM-1. Blood samples from patients with FMF according to Livneh criteria followed in the French FMF national center and carrying two pathogenic MEFV mutations were collected. Serum level of sTREM-1 was assessed using ELISA. Demographic data, presence of FMF attack, association with histologically proven AA amyloidosis, and blood levels of C-reactive protein (CRP), serum amyloid A (SAA) protein, and creatinine were collected. TREM-1 was available in 56 patients (33.9% male, mean age 43 yr); AA amyloidosis was associated in six patients (19.6% in FMF). Mean sTREM-1 level did not differ significantly between patients having an attack or not and there was also no significant correlation between the level of sTREM-1 and CRP and SAA protein. However, the mean rate of sTREM-1 was significantly higher among FMF patients with AA amyloidosis versus without, though the concomitant SAA protein level was normal. Serum level of sTREM-1 was higher in patients with amyloidosis even though the concomitant SAA protein level was normal. sTREM-1 plasma levels could be an accurate tool to specifically identify FMF patients with amyloidosis.

Hypoxia and Inflammation as a Consequence of β-Fibril Accumulation: A Perspective View for New Potential Therapeutic Targets

Amyloidoses are heterogeneous diseases that result from the deposition of toxic insoluble β-sheet fibrillar protein aggregates in different tissues. The cascade of molecular events leading to amyloidoses and to the related clinical manifestations is not completely understood. Nevertheless, it is known that tissue damage associated to this disease involves alteration of tissue architecture, interaction with cell surface receptors, inflammation elicited by the amyloid protein deposition, oxidative stress, and apoptosis. However, another important aspect to consider is that systemic protein massive deposition not only subverts tissue architecture but also determines a progressive cellular hypertrophy and dilation of the extracellular space enlarging the volume of the organ. Such an alteration increases the distance between cells and vessels with a drop in pO₂ that, in turn, causes both necrotic cell death and activation of the hypoxia transcription factor HIF-1α. Herewith, we propose the hypothesis that both cell death and hypoxia represent two important events for the pathogenesis of damage and progression of amyloidoses. In fact, molecules released by necrotic cells activate inflammatory cells from one side while binding to HIF-1α-dependent membrane receptors expressed on hypoxic parenchymal cells on the other side. This latter event generates a signaling cascade triggering NFκB activation and chronic inflammation. Finally, we also suggest that this scenario, once proved and detailed, might suggest important targets for new therapeutic interventions.

Chirality-Selected Chemical Modulation of Amyloid Aggregation

Due to the composed α-helical/β-strand structures, β-amyloid peptide (Aβ) is sensitive to chiral environments. The orientation and chirality of the Aβ strand strongly influence its aggregation. Aβ-formed fibrils have a cascade of chirality. Therefore, for selectively targeting amyloid aggregates, chirality preference can be one key issue. Inspired by the natural stereoselectivity and the β-sheet structure, herein, we synthesized a series of d- and l-amino acid-modified polyoxometalate (POM) derivatives, including positively charged amino acids (d-His and l-His) and negatively charged (d-Glu and l-Glu) and hydrophobic amino acids (d-Leu, l-Leu, d-Phe, and l-Phe), to modulate Aβ aggregation. Intriguingly, Phe-modified POMs showed a stronger inhibition effect than other amino acid-modified POMs, as evidenced by multiple biophysical and spectral assays, including fluorescence, circular dichroism, NMR, molecular dynamic simulations, and isothermal titration calorimetry. More importantly, d-Phe-modified POM had an 8-fold stronger inhibition effect than l-Phe-modified POM, indicating high enantioselectivity. Furthermore, in vivo studies demonstrated that the chiral POM derivatives crossed the blood-brain barrier, extended the life span of AD transgenic Caenorhabditis elegans CL2006 strain, and had low cytotoxicity, even at a high dosage.

Early Detection of Multiorgan Light-Chain Amyloidosis by Whole-Body 18F-Florbetapir PET/CT

Immunoglobulin light-chain (AL) amyloidosis affects multiple systemic organs. However, determination of the precise extent of organ involvement remains challenging. Targeted amyloid imaging with ¹⁸F-florbetapir PET/CT offers the potential to detect AL deposits in multiple organs. The primary aim of this study was to determine the distribution and frequency of AL deposits in the various organs of subjects with systemic AL amyloidosis using ¹⁸F-florbetapir PET/CT. Methods: This prospective study included 40 subjects with biopsy-proven AL amyloidosis including active AL amyloidosis (n = 30) or AL amyloidosis in hematologic remission for more than 1 y (n = 10). All subjects underwent ¹⁸F-florbetapir PET/CT, skull base to below the kidney scan field, from 60 to 90 min after injection of radiotracer. Volume-of-interest measurements of SUV_max were obtained using Hermes software for the parotid gland, tongue, thyroid, lung, gastric wall, pancreas, spleen, kidney, muscle, abdominal fat, lower thoracic spine, vertebral body, and humeral head. Uptake in each organ was visually compared with that in spine bone marrow. An SUV_max of at least 2.5 was considered abnormal in all organs other than the liver. Results: Compared with the international consensus definition of organ involvement, ¹⁸F-florbetapir PET/CT identified amyloid deposits in substantially higher percentages of subjects for several organ systems, including parotid gland (50% vs. 3%), tongue (53% vs. 10%), and lung (35% vs. 10%). In several organ systems, including kidney (13% vs. 28%) and abdominal wall fat (10% vs. 13%), PET identified involvement in fewer subjects than did international consensus. Quantitative analysis of ¹⁸F-florbetapir PET/CT revealed more frequent organ involvement than did visual analysis in the tongue, thyroid, lung, pancreas, kidney, muscle, and humeral head. Extensive organ amyloid deposits were observed in active AL as well as in AL remission cohorts, and in both cardiac and noncardiac AL cohorts. Conclusion: ¹⁸F-florbetapir PET/CT detected widespread organ amyloid deposition in subjects with both active AL and AL hematologic remission. In most instances, amyloid deposits in the various organs were not associated with clinical symptoms and, thus, were unrecognized. Early recognition of systemic organ involvement may help tailor treatment, and noninvasive monitoring of organ-level disease may guide management with novel fibril-resorbing therapies.

Symptomatic involvement of the stomach and duodenum as initial presentation of AL amyloidosis

Primary systemic or amyloid light chain (AL) amyloidosis is a multisystem disorder with myriad presentations. Although it can involve the upper gastrointestinal tract in 8% of cases, symptomatic involvement is exceedingly rare. We chronicle here a case of postprandial epigastric pain associated with AL amyloidosis involving the stomach and duodenum. Pathological examination of endoscopic biopsy using Congo red staining confirmed the diagnosis. In order to establish the underlying aetiology of AL amyloidosis, the patient underwent extensive workup. Eventually, she was diagnosed with multiple myeloma based on the standard set of investigations. This paper underscores the importance of clinical suspicion of amyloidosis in patients presenting with non-specific gastrointestinal symptoms and highlights the role of endoscopic biopsy to confirm the amyloid deposition. Since gastrointestinal amyloidosis is a disease with a poor prognosis, early diagnosis and treatment are particularly warranted.

Localized Sinonasal Amyloidosis

Localized amyloidosis involving the nasal mucosa is rare, with only 38 published cases reported to date. We report a case of amyloidosis localized to the sinonasal tract. A 61-year-old man presented with a 1-year history of left-sided nasal obstruction. Endoscopic examination and computed tomography revealed the presence of a nasal mass originating from the left inferior turbinate. The patient subsequently underwent an examination under anesthesia and an excision biopsy of the nasal mass. Histology confirmed amyloidosis with no immunospecific stains. Systemic amyloidosis testing was negative, leading to a diagnosis of localized sinonasal amyloidosis of nonamyloid A (AA) subtype. To our knowledge, this is the second reported case of non-AA subtype of the sinonasal tract. The patient was managed conservatively and is currently under close follow-up.

Role of domain interactions in the aggregation of full-length immunoglobulin light chains

Amyloid light-chain (LC) amyloidosis is a protein misfolding disease in which the aggregation of an overexpressed antibody LC from a clonal plasma cell leads to organ toxicity and patient death if left untreated. While the overall dimeric architecture of LC molecules is established, with each LC composed of variable (V_L) and constant (C_L) domains, the relative contributions of LC domain-domain interfaces and intrinsic domain stabilities to protection against LC aggregation are not well understood. To address these topics we have engineered a number of domain-destabilized LC mutants and used solution NMR spectroscopy to characterize their structural properties and intrinsic stabilities. Moreover, we used fluorescence spectroscopy to assay their aggregation propensities. Our results point to the importance of both dimerization strength and intrinsic monomer stability in stabilizing V_L domains against aggregation. Notably, in all cases considered V_L domains aggregate at least 10-fold faster than full-length LCs, establishing the important protective role of C_L domains. A strong protective coupling is found between V_L-V_L and C_L-C_L dimer interfaces, with destabilization of one interface adversely affecting the stability of the other. Fibril formation is observed when either the V_L or C_L domain in the full-length protein is severely destabilized (i.e., where domain unfolding free energies are less than 2 kcal/mol). The important role of C_L domains in preventing aggregation highlights the potential of the C_L-C_L interface as a target for the development of drugs to stabilize the dimeric LC structure and hence prevent LC amyloidosis.

Renal-limited AL amyloidosis - a diagnostic and management dilemma

Background

Amyloidosis is a disorder caused by extracellular tissue deposition of insoluble fibrils which may result in a wide spectrum of symptoms depending upon their types, sites and amount of deposition. Amyloidosis can be divided into either systemic or localized disease.

Case presentation

We present a case of a middle-aged gentleman who presented with persistent nephrotic syndrome with worsening renal function. Repeated renal biopsies showed the presence of renal-limited AL amyloidosis. Systemic amyloidosis workup was unremarkable apart from a slightly raised band of IgG lambda level with no associated immunoparesis. The nephrotic syndrome and renal histology did not improve over a 3-year period despite being given two courses of chemotherapies.

Conclusion

We hope that early recognition of this unusual localised presentation of renal- limited AL Amyloidosis and its poor response to conventional treatment can alert the nephrologist to the potential existence of this rare condition.

A case of multiple myeloma initially presenting as hematemesis

A few cases of multiple myeloma with gastrointestinal bleeding have been reported, but hematemesis is rarely encountered as an initial symptom of multiple myeloma. Here we report a case of multiple myeloma with an initial symptom of hematemesis. Gastroscopy revealed ulceration in the angulus of the stomach. Colonoscopy revealed many ulcers in the ascending colon. A definite diagnosis of gastrointestinal amyloidosis was made using tissue biopsy. A definite diagnosis of multiple myeloma was made using bone marrow puncture. Hematemesis may be an initial symptom of multiple myeloma. A diagnosis of amyloidosis-induced hematemesis should be considered in patients with multiple myeloma.