Amyloid-related Disease Research Articles

An AIE-Active NIR Fluorescent Probe with Good Water Solubility for the Detection of Aβ1-42 Aggregates in Alzheimer's Disease.

Alzheimer's disease (AD), an amyloid-related disease, seriously endangers the health of elderly individuals. According to current research, its main pathogenic factor is the amyloid protein, which is a kind of fibrillar aggregate formed by noncovalent self-assembly of proteins. Based on the characteristics of aggregation-induced emission (AIE), a bislactosyl-decorated tetraphenylethylene (TPE) molecule TMNL (TPE + malononitrile + lactose), bearing two malononitrile substituents, was designed and synthesized in this work. The amphiphilic TMNL could self-assemble into fluorescent organic nanoparticles (FONs) with near-infrared (NIR) fluorescence emission in physiological PBS (phosphate buffered saline), achieving excellent fluorescent enhancement (47-fold) upon its combination with Aβ1-42 fibrils. TMNL was successfully applied to image Aβ1-42 plaques in the brain tissue of AD transgenic mice, and due to the AIE properties of TMNL, no additional rinsing process was necessary. It is believed that the probe reported in this work should be useful for the sensitive detection and accurate localization mapping of Aβ1-42 aggregates related to Alzheimer's disease.

DES-Amyloidoses "Amyloidoses through the looking-glass": A knowledgebase developed for exploring and linking information related to human amyloid-related diseases.

More than 30 types of amyloids are linked to close to 50 diseases in humans, the most prominent being Alzheimer’s disease (AD). AD is brain-related local amyloidosis, while another amyloidosis, such as AA amyloidosis, tends to be more systemic. Therefore, we need to know more about the biological entities’ influencing these amyloidosis processes. However, there is currently no support system developed specifically to handle this extraordinarily complex and demanding task. To acquire a systematic view of amyloidosis and how this may be relevant to the brain and other organs, we needed a means to explore "amyloid network systems" that may underly processes that leads to an amyloid-related disease. In this regard, we developed the DES-Amyloidoses knowledgebase (KB) to obtain fast and relevant information regarding the biological network related to amyloid proteins/peptides and amyloid-related diseases. This KB contains information obtained through text and data mining of available scientific literature and other public repositories. The information compiled into the DES-Amyloidoses system based on 19 topic-specific dictionaries resulted in 796,409 associations between terms from these dictionaries. Users can explore this information through various options, including enriched concepts, enriched pairs, and semantic similarity. We show the usefulness of the KB using an example focused on inflammasome-amyloid associations. To our knowledge, this is the only KB dedicated to human amyloid-related diseases derived primarily through literature text mining and complemented by data mining that provides a novel way of exploring information relevant to amyloidoses.

NMR Studies of the Ion Channel-Forming Human Amyloid-β with Zinc Ion Concentrations.

Alzheimer’s disease (AD) is classified as an amyloid-related disease. Amyloid beta (Aβ) is a transmembrane protein known to play a major role in the pathogenesis of AD. These Aβ proteins can form ion channels or pores in the cell membrane. Studies have elucidated the structure of the transmembrane domain of Aβ ion channels. In addition, various studies have investigated substances that block or inhibit the formation of Aβ ion channels. Zinc ions are considered as potential inhibitors of AD. In this study, we focused on the transmembrane domain and some external domains of the Aβ protein (hAPP-TM), and solution-state NMR was used to confirm the effect on residues of the protein in the presence of zinc ions. In addition, we sought to confirm the structure and orientation of the protein in the presence of the bicelle using solid-state NMR.

Targeting the Amyloid-β Fibril Surface with a Constrained Helical Peptide Inhibitor.

Amyloid-β (Aβ) oligomers are well-known toxic molecular species associated with Alzheimer's disease. Recent discoveries of the ability of amyloid fibril surfaces to convert soluble proteins into toxic oligomers suggested that these surfaces could serve as therapeutic targets for intervention. We have shown previously that a short helical peptide could be a key structural motif that can specifically recognize the K16-E22 region of the Aβ40 fibril surface with an affinity at the level of several micromolar. Here, we demonstrate that in-tether chiral center-induced helical stabilized peptides could also recognize the fibril surfaces, effectively inhibiting the surface-mediated oligomerization of Aβ40. Moreover, through extensive computational sampling, we observed two distinct ways in which the peptide inhibitors recognize the fibril surface. Apart from a binding mode that, in accord with the original design, involves hydrophobic side chains at the binding interface, we observed much more frequently another binding mode in which the hydrophobic staple interacts directly with the fibril surface. The affinity of the peptides for the fibril surface could be adjusted by tuning the hydrophobicity of the staple. The best candidate investigated here exhibits a submicromolar affinity (∼0.75 μM). Collectively, this work opens an avenue for the rational design of candidate drugs with stapled peptides for amyloid-related disease.

Charge and charge-pair mutations alter the rate of assembly and structural properties of apolipoprotein C-II amyloid fibrils.

The misfolding, aggregation, and accumulation of proteins as amyloid fibrils is a defining characteristic of several debilitating diseases. Human apolipoprotein C-II (apoC-II) amyloid fibrils are representative of the fibrils formed by a number of plasma apolipoproteins implicated in amyloid-related disease. Previous structural analyses identified a buried charge pair between residues K30 and D69 within apoC-II amyloid fibrils. We have investigated the effects of amino acid substitutions of these residues on apoC-II fibril formation. Two point mutations of apoC-II, D69K and K30D, as well as a reversed ion-pair mutant containing both mutations (KDDK) were generated. Fibril formation by the double mutant, apoC-II KDDK, and apoC-II D69K was enhanced compared to that of wild-type (WT) apoC-II, while apoC-II K30D lacked the ability to form fibrils under standard conditions. Structural analyses showed that WT apoC-II, apoC-II D69K, and apoC-II KDDK fibrils have similar secondary structures and morphologies. Size distribution analyses revealed that apoC-II D69K fibrils have a broader range of fibril sizes while apoC-II KDDK fibrils showed an increased frequency of closed fibrillar loops. ApoC-II D69K fibrils exhibited reduced thioflavin T binding capacity compared to that of fibrils formed by WT apoC-II and apoC-II KDDK. These results indicate that specific charge and charge-pair mutations within apoC-II significantly alter the ability to form fibrils and that position 69 within apoC-II plays a key role in the rate-limiting step of apoC-II fibril formation.

Role of oligomers in the amyloidogenesis of primary cutaneous amyloidosis

Primary cutaneous amyloidosis (PCA) describes a heterogeneous group of cutaneous diseases characterized by amyloid deposition; this may manifest as macules, papules, or nodules, depending on the subtype involved. To date, relatively little is known about the process of amyloidogenesis in the skin; however, investigators recently have identified small amyloid species, known as oligomers, which give rise to large amyloid fibrillar aggregates. The purpose of the current study was to identify small oligomers in patients with PCA using novel immunohistochemical techniques and to examine our findings in light of previous hypotheses of amyloid formation in these diseases. Six cases of PCA were analyzed using Congo red, thioflavin S, and hematoxylin-eosin. We also analyzed these samples with the novel oligomer-specific conformational antibody I-11 to detect the small, misfolded protein oligomers. Semiquantitative analysis was performed on these samples to grade the amount of amyloid aggregates and oligomers detected in the skin samples with light and polarized microscopy. In the cases examined, we detected intracellular oligomers in the basal cell layer of the epidermis and the surrounding cells in the dermis. We also were able to detect large aggregates of amyloid in our samples and to correlate the relationship of oligomers to amyloid aggregates in accordance with previous studies on cutaneous amyloidosis and other amyloid-related diseases. Small sample size is a limitation. PCA is an amyloid-related disease that likely follows a similar mechanism as other more intensively studied amyloid diseases.

Structural Basis for the Recognition and Cross-linking of Amyloid Fibrils by Human Apolipoprotein E

Apolipoprotein (apo) E is a well characterized lipid-binding protein in plasma that also exists as a common nonfibrillar component of both cerebral and systemic amyloid deposits. A genetic link between a common isoform of apoE, apoE4, and the incidence of late onset Alzheimer disease has drawn considerable attention to the potential roles of apoE in amyloid-related disease. We examined the interactions of apoE with amyloid fibrils composed of apoC-II and the amyloid-beta (Abeta) peptide. Aggregates of apoE with Abeta and apoC-II are found in Alzheimer and atherosclerotic plaques, respectively. Sedimentation velocity and fibril size distribution analysis showed that apoE3 and E4 isoforms bind and noncovalently cross-link apoC-II fibrils in a similar manner. This ability to cross-link apoC-II fibrils was abolished by the dissociation of the apoE tetramer to monomers or by thrombin cleavage to yield separate N- and C-terminal domains. Preparative ultracentrifuge binding studies indicated that apoE and the isolated N- and C-terminal domains of apoE bind with submicromolar affinities to both apoC-II and Abeta fibrils. Fluorescence quenching and resonance energy transfer experiments confirmed that both domains of apoE interact with apoC-II fibrils and demonstrated that the binding of the isolated N-terminal domain of apoE to apoC-II or Abeta fibrils is accompanied by a significant conformational change with helix three of the domain moving relative to helix one. We propose a model involving the interaction of apoE with patterns of aligned residues that could explain the general ability of apoE to bind to a diverse range of amyloid fibrils.

Autologe Stammzelltransplantation bei progredienter Amyloidose ist mit deutlich erhöhter transplantationsassoziierter Toxizität behaftet

Amyloid light-chain (AL) amyloidosis is a disorder of plasma cells in which depositions of immunoglobulin light-chain fragments cause progressive organ failure and death with a median survival of one year, but autologous stem-cell transplantation can induce high response rates, especially in isolated renal involvement. Six patients aged between 43 and 59 years were diagnosed with AL-amyloidosis and had stem cells mobilized with either recombinant human granulocyte colony-stimulating factor (rhG-CSF) alone (n = 2) or cyclophosphamide (2-4 g/m(2)) and rhG-CSF (n = 4). All six patients had kidney involvement and nephrotic syndrome, four had cardiac involvement and two involvement of the vascular, nervous and gastrointestinal systems. Five of the patients received high-dose melphalan (200 mg/m(2)) and autologous blood stem-cell support. One patient died as a result of sepsis after stem-cell mobilization. The other five patients received high-dose melphalan but experienced severe toxicity. One patient died as the result of gastrointestinal perforation on day 6, one presented with hyperfibrinolysis and spontaneous rupture of the spleen, and another experienced severe bleeding of the gastrointestine, tachyarrhythmia and hemolytic anemia. Four patients had acute renal failure: three required hemodialysis and one underwent renal transplant 21 months later. Restaging after a follow-up of 31-52 months revealed reversal of nephrotic syndrome in all three patients who regained adequate renal function. With respect to cardiac involvement (n = 2), one patient showed a decrease in NYHA class from II to I but baseline wall thickness remained stable. Treatment of selected patients with AL-amyloidosis by high-dose melphalan and stem-cell support results in reversal of amyloid-related disease in a substantial proportion of patients and improved survival.

An overview of the use of high-dose melphalan with autologous stem cell transplantation for the treatment of AL amyloidosis.

Primary or AL amyloidosis results from a plasma cell dyscrasia in which fibrillar light chain protein deposition leads to organ failure and death. Standard treatment for AL amyloidosis has been oral melphalan and prednisone. However, this form of treatment modifies the natural history of this lethal disease only marginally, extending median survival from 13 months following diagnosis to 17 months. At Boston University Medical Center, we have developed treatment protocols using high-dose intravenous melphalan with autologous peripheral blood stem cell transplantation (HDM/SCT) to treat AL amyloidosis, and we have treated over 200 patients with HDM/SCT during the past six years. This extensive experience has shown that patients with AL amyloidosis, despite multisystem involvement and compromised organ function can tolerate this aggressive form of treatment. Furthermore, HDM/SCT results in durable hematologic responses in a substantial proportion of patients, and such responses are associated with clinical improvement, decreased amyloid-related organ dysfunction, and prolonged survival. However, toxicity from treatment is high (overall peri-transplant mortality, 14%), particularly for those patients with clinically significant cardiac involvement. For this reason, we believe a multidisciplinary management approach is essential when using HDM/SCT for treatment of AL amyloidosis. Based on our experience, we believe that HDM/SCT is the treatment of choice for patients with AL amyloidosis who have a good performance status and limited cardiac involvement at the time of diagnosis. HDM/SCT offers the best chance for hematologic remission, prolongation of survival, and reversal of amyloid-related disease. At the same time, we believe that HDM/SCT should continue to be examined in the context of clinical trials, directed at developing approaches to broaden the applicability of this therapy by minimizing toxicity and to increase the likelihood of complete hematologic responses.

Orthotopic liver transplantation for familial amyloidotic polyneuropathy: A pathological study

Familial amyloidotic polyneuropathy (FAP), a hereditary form of systemic amyloidosis with clinically significant neuropathy and cardiomyopathy, is caused by a genetic defect of the transthyretin gene, which is mostly synthesized in the liver. Orthotopic liver transplantation (OLT) is thought to eliminate the amyloidogenic protein and currently is the only definitive treatment for this disorder. The aim of this study was to define the distribution and extent of amyloid deposition in tissues from these patients and evaluate the suitability of the resected FAP livers for transplantation into non-FAP patients. Surgical specimens from 14 patients removed at the time of OLT and autopsy tissues from 3 of the 14 were examined histologically using hematoxylin and eosin and Congo red-stained sections. The extent of amyloid deposits was evaluated, semiquantitatively graded from negative to marked, and correlated with clinical course and patient outcome. Amyloid deposits were consistently seen in hilar and vagus nerves. Liver lobular involvement was minimal in 1 and absent in the other 13 cases, with portal arterial amyloid deposits seen in 7 cases. At autopsy, extensive amyloid deposition in the heart was seen in all 3 cases with involvement of the conduction system. The extent of amyloid deposition at OLT did not correlate with the duration of symptoms before OLT or patient outcome after OLT. In conclusion, liver parenchymal involvement in FAP is minimal, and these explants are suitable for grafting in non-FAP patients. The recipients of such grafts must be carefully observed for the development of any amyloid-related disease, particularly cardiomyopathy. Of the tissues removed at OLT, the histopathologic confirmation of FAP is most consistently made by the examination of hilar and vagus nerves.