Browsing by Subject "amyloid"
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Item [(11)C]PiB PET in Gerstmann-Sträussler-Scheinker disease(e-Century Publishing Corporation, 2016) Deters, Kacie D.; Risacher, Shannon L.; Yoder, Karmen K.; Oblak, Adrian L.; Unverzagt, Frederick W.; Murrell, Jill R.; Epperson, Francine; Tallman, Eileen F.; Quaid, Kimberly A.; Farlow, Martin R.; Saykin, Andrew J.; Ghetti, Bernardino; Department of Pathology & Laboratory Medicine, IU School of MedicineGerstmann-Sträussler-Scheinker Disease (GSS) is a familial neurodegenerative disorder characterized clinically by ataxia, parkinsonism, and dementia, and neuropathologically by deposition of diffuse and amyloid plaques composed of prion protein (PrP). The purpose of this study was to evaluate if [(11)C]Pittsburgh Compound B (PiB) positron emission tomography (PET) is capable of detecting PrP-amyloid in PRNP gene carriers. Six individuals at risk for GSS and eight controls underwent [(11)C]PiB PET scans using standard methods. Approximately one year after the initial scan, each of the three asymptomatic carriers (two with PRNP P102L mutation, one with PRNP F198S mutation) underwent a second [(11)C]PiB PET scan. Three P102L carriers, one F198S carrier, and one non-carrier of the F198S mutation were cognitively normal, while one F198S carrier was cognitively impaired during the course of this study. No [(11)C]PiB uptake was observed in any subject at baseline or at follow-up. Neuropathologic study of the symptomatic individual revealed PrP-immunopositive plaques and tau-immunopositive neurofibrillary tangles in cerebral cortex, subcortical nuclei, and brainstem. PrP deposits were also numerous in the cerebellar cortex. This is the first study to investigate the ability of [(11)C]PiB PET to bind to PrP-amyloid in GSS F198S subjects. This finding suggests that [(11)C]PiB PET is not suitable for in vivo assessment of PrP-amyloid plaques in patients with GSS.Item A cell-based high-throughput screening method to directly examine transthyretin amyloid fibril formation at neutral pH(Elsevier, 2019-07-19) Ueda, Mitsuharu; Okada, Masamitsu; Mizuguchi, Mineyuki; Kluve-Beckerman, Barbara; Kanenawa, Kyosuke; Isoguchi, Aito; Misumi, Yohei; Tasaki, Masayoshi; Ueda, Akihiko; Kanai, Akinori; Sasaki, Ryoko; Masuda, Teruaki; Inoue, Yasuteru; Nomura, Toshiya; Shinriki, Satoru; Shuto, Tsuyoshi; Kai, Hirofumi; Yamashita, Taro; Matsui, Hirotaka; Benson, Merrill D.; Ando, Yukio; Pathology and Laboratory Medicine, School of MedicineTransthyretin (TTR) is a major amyloidogenic protein associated with hereditary (ATTRm) and nonhereditary (ATTRwt) intractable systemic transthyretin amyloidosis. The pathological mechanisms of ATTR-associated amyloid fibril formation are incompletely understood, and there is a need for identifying compounds that target ATTR. C-terminal TTR fragments are often present in amyloid-laden tissues of most patients with ATTR amyloidosis, and on the basis of in vitro studies, these fragments have been proposed to play important roles in amyloid formation. Here, we found that experimentally-formed aggregates of full-length TTR are cleaved into C-terminal fragments, which were also identified in patients' amyloid-laden tissues and in SH-SY5Y neuronal and U87MG glial cells. We observed that a 5-kDa C-terminal fragment of TTR, TTR81–127, is highly amyloidogenic in vitro, even at neutral pH. This fragment formed amyloid deposits and induced apoptosis and inflammatory gene expression also in cultured cells. Using the highly amyloidogenic TTR81–127 fragment, we developed a cell-based high-throughput screening method to discover compounds that disrupt TTR amyloid fibrils. Screening a library of 1280 off-patent drugs, we identified two candidate repositioning drugs, pyrvinium pamoate and apomorphine hydrochloride. Both drugs disrupted patient-derived TTR amyloid fibrils ex vivo, and pyrvinium pamoate also stabilized the tetrameric structure of TTR ex vivo in patient plasma. We conclude that our TTR81–127–based screening method is very useful for discovering therapeutic drugs that directly disrupt amyloid fibrils. We propose that repositioning pyrvinium pamoate and apomorphine hydrochloride as TTR amyloid-disrupting agents may enable evaluation of their clinical utility for managing ATTR amyloidosis.Item Empirically Defining Trajectories of Late-Life Cognitive and Functional Decline(IOS, 2015-11) Hochstetler, Helen; Trzepacz, Paula T.; Wang, Shufang; Yu, Peng; Case, Michael; Henley, David B.; Degenhardt, Elisabeth; Leoutsakos, Jeannie-Marie; Lyketsos, Constantine G.; Department of Psychiatry, IU School of MedicineBackground: Alzheimer’s disease (AD) is associated with variable cognitive and functional decline, and it is difficult to predict who will develop the disease and how they will progress. Objective: This exploratory study aimed to define latent classes from participants in the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database who had similar growth patterns of both cognitive and functional change using Growth Mixture Modeling (GMM), identify characteristics associated with those trajectories, and develop a decision tree using clinical predictors to determine which trajectory, as determined by GMM, individuals will most likely follow. Methods: We used ADNI early mild cognitive impairment (EMCI), late MCI (LMCI), AD dementia, and healthy control (HC) participants with known amyloid-β status and follow-up assessments on the Alzheimer’s Disease Assessment Scale - Cognitive Subscale or the Functional Activities Questionnaire (FAQ) up to 24 months postbaseline. GMM defined trajectories. Classification and Regression Tree (CART) used certain baseline variables to predict likely trajectory path. Results: GMM identified three trajectory classes (C): C1 (n = 162, 13.6%) highest baseline impairment and steepest pattern of cognitive/functional decline; C3 (n = 819, 68.7%) lowest baseline impairment and minimal change on both; C2 (n = 211, 17.7%) intermediate pattern, worsening on both, but less steep than C1. C3 had fewer amyloid- or apolipoprotein-E ɛ4 (APOE4) positive and more healthy controls (HC) or EMCI cases. CART analysis identified two decision nodes using the FAQ to predict likely class with 82.3% estimated accuracy. Conclusions: Cognitive/functional change followed three trajectories with greater baseline impairment and amyloid and APOE4 positivity associated with greater progression. FAQ may predict trajectory class.Item Florbetaben PET imaging to detect amyloid beta plaques in Alzheimer disease: Phase 3 study(Elsevier, 2015) Sabri, Osama; Sabbagh, Marwan N.; Seibyl, John; Barthel, Henryk; Akatsu, Hiroyasu; Ouchi, Yasuomi; Senda, Kohei; Murayama, Shigeo; Ishii, Kenji; Takao, Masaki; Beach, Thomas G.; Rowe, Christopher C.; Leverenz, James B.; Ghetti, Bernardino; Ironside, James W.; Catafau, Ana M.; Stephens, Andrew W.; Mueller, Andre; Koglin, Norman; Hoffman, Anja; Roth, Katrin; Reininger, Cornelia; Schulz-Schaeffer, Walter J.; Department of Pathology and Laboratory Medicine, IU School of MedicineBackground Evaluation of brain β-amyloid by positron emission tomography (PET) imaging can assist in the diagnosis of Alzheimer disease (AD) and other dementias. Methods Open-label, nonrandomized, multicenter, phase 3 study to validate the 18F-labeled β-amyloid tracer florbetaben by comparing in vivo PET imaging with post-mortem histopathology. Results Brain images and tissue from 74 deceased subjects (of 216 trial participants) were analyzed. Forty-six of 47 neuritic β-amyloid-positive cases were read as PET positive, and 24 of 27 neuritic β-amyloid plaque-negative cases were read as PET negative (sensitivity 97.9% [95% confidence interval or CI 93.8–100%], specificity 88.9% [95% CI 77.0–100%]). In a subgroup, a regional tissue-scan matched analysis was performed. In areas known to strongly accumulate β-amyloid plaques, sensitivity and specificity were 82% to 90%, and 86% to 95%, respectively. Conclusions Florbetaben PET shows high sensitivity and specificity for the detection of histopathology-confirmed neuritic β-amyloid plaques and may thus be a valuable adjunct to clinical diagnosis, particularly for the exclusion of AD.Item Genetic variants and functional pathways associated with resilience to Alzheimer’s disease(Oxford, 2020-08-25) Dumitrescu, Logan; Mahoney, Emily R; Mukherjee, Shubhabrata; Lee, Michael L; Bush, William S; Engelman, Corinne D; Lu, Qiongshi; Fardo, David W; Trittschuh, Emily H; Mez, Jesse; Kaczorowski, Catherine; Hernandez Saucedo, Hector; Widaman, Keith F; Buckley, Rachel; Properzi, Michael; Mormino, Elizabeth; Yang, Hyun-Sik; Harrison, Tessa; Hedden, Trey; Nho, Kwangsik; Andrews, Shea J; Tommet, Doug; Hadad, Niran; Sanders, R Elizabeth; Ruderfer, Douglas M; Gifford, Katherine A; Moore, Annah M; Cambronero, Francis; Zhong, Xiaoyuan; Raghavan, Neha S.; Vardarajan, Badri; Pericak-Vance, Margaret A.; Farrer, Lindsay A.; Wang, Li-San; Cruchaga, Carlos; Schellenberg, Gerard; Cox, Nancy J.; Haines, Jonathan L,; Keene, C. Dirk; Saykin, Andrew J.; Larson, Eric B.; Sperling, Reisa A.; Mayeux, Richard; Bennett, David A.; Schneider, Julie A.; Crane, Paul K.; Jefferson, Angela L.; Hohman, Timothy J.; Radiology and Imaging Sciences, School of MedicineApproximately 30% of older adults exhibit the neuropathological features of Alzheimer’s disease without signs of cognitive impairment. Yet, little is known about the genetic factors that allow these potentially resilient individuals to remain cognitively unimpaired in the face of substantial neuropathology. We performed a large, genome-wide association study (GWAS) of two previously validated metrics of cognitive resilience quantified using a latent variable modelling approach and representing better-than-predicted cognitive performance for a given level of neuropathology. Data were harmonized across 5108 participants from a clinical trial of Alzheimer’s disease and three longitudinal cohort studies of cognitive ageing. All analyses were run across all participants and repeated restricting the sample to individuals with unimpaired cognition to identify variants at the earliest stages of disease. As expected, all resilience metrics were genetically correlated with cognitive performance and education attainment traits (P-values < 2.5 × 10−20), and we observed novel correlations with neuropsychiatric conditions (P-values < 7.9 × 10−4). Notably, neither resilience metric was genetically correlated with clinical Alzheimer’s disease (P-values > 0.42) nor associated with APOE (P-values > 0.13). In single variant analyses, we observed a genome-wide significant locus among participants with unimpaired cognition on chromosome 18 upstream of ATP8B1 (index single nucleotide polymorphism rs2571244, minor allele frequency = 0.08, P = 2.3 × 10−8). The top variant at this locus (rs2571244) was significantly associated with methylation in prefrontal cortex tissue at multiple CpG sites, including one just upstream of ATPB81 (cg19596477; P = 2 × 10−13). Overall, this comprehensive genetic analysis of resilience implicates a putative role of vascular risk, metabolism, and mental health in protection from the cognitive consequences of neuropathology, while also providing evidence for a novel resilience gene along the bile acid metabolism pathway. Furthermore, the genetic architecture of resilience appears to be distinct from that of clinical Alzheimer’s disease, suggesting that a shift in focus to molecular contributors to resilience may identify novel pathways for therapeutic targets.Item GWAS of longitudinal amyloid accumulation on 18F-florbetapir PET in Alzheimer’s disease implicates microglial activation gene IL1RAP.(Oxford UP, 2015-10) Ramanan, Vijay K.; Risacher, Shannon L.; Nho, Kwangsik; Kim, Sungeun; Shen, Li; McDonald, Brenna C.; Yoder, Karmen K.; Hutchins, Gary D.; West, John D.; Tallman, Eileen F.; Gao, Sujuan; Foroud, Tatiana M.; Farlow, Martin R.; De Jager, Philip L.; Bennett, David A.; Aisen, Paul S.; Petersen, Ronald C.; Jack, Clifford R.; Toga, Arthur W.; Green, Robert C.; Jagust, William J.; Weiner, Michael W.; Saykin, Andrew J.; Department of Medical and Molecular Genetics, IU School of MedicineIn a genome-wide study, Ramanan et al. discover an association between the microglial activation gene IL1RAP and higher rates of amyloid plaque accumulation as measured by PET in prodromal Alzheimer’s disease. Activated microglia may be crucial in amyloid clearance, and targeting the interleukin-1/IL1RAP pathway may be a potential therapeutic approach.Item Hereditary systemic immunoglobulin light-chain amyloidosis(American Society of Hematology, 2015-05) Benson, Merrill D.; Liepnieks, Juris J.; Kluve-Beckerman, Barbara; Department of Pathology and Laboratory Medicine, IU School of MedicineSeveral members of a family died from renal failure as a result of systemic amyloidosis. Extensive studies to detect previously documented gene mutations associated with amyloidosis failed to identify a causative factor. In search of the genetic basis for this syndrome, amyloid fibrils were isolated from renal tissue of a member of the kin who died while on renal dialysis. Amino acid sequencing of isolated amyloid protein identified sequences compatible with the constant region of the immunoglobulin κ light-chain. Isolation and characterization of κ light-chain protein from serum of an affected member of the kindred revealed mutation in the constant region of κ light-chain, with cysteine replacing serine at amino acid residue 131. This mutation (Ser131Cys) was confirmed by DNA analysis, which identified a single-base change of cytosine to guanine at the second position of codon 131 of the κ light-chain gene (TCT131TGT). DNA analysis of members of the extended family revealed transmission of the Ser131Cys mutation and association with systemic amyloidosis. This amyloid light-chain (AL) amyloidosis, which is a hereditary type of amyloidosis and not the result of a monoclonal plasma cell dyscrasia, may be misdiagnosed and lead to inappropriate chemotherapy.Item Herpes Simplex Virus Type 1 and Other Pathogens are Key Causative Factors in Sporadic Alzheimer’s Disease(IOS, 2015) Harris, Steven A.; Harris, Elizabeth A.; Medicine, School of MedicineThis review focuses on research in epidemiology, neuropathology, molecular biology, and genetics regarding the hypothesis that pathogens interact with susceptibility genes and are causative in sporadic Alzheimer’s disease (AD). Sporadic AD is a complex multifactorial neurodegenerative disease with evidence indicating coexisting multi-pathogen and inflammatory etiologies. There are significant associations between AD and various pathogens, including Herpes simplex virus type 1 (HSV-1), Cytomegalovirus, and other Herpesviridae, Chlamydophila pneumoniae, spirochetes, Helicobacter pylori, and various periodontal pathogens. These pathogens are able to evade destruction by the host immune system, leading to persistent infection. Bacterial and viral DNA and RNA and bacterial ligands increase the expression of pro-inflammatory molecules and activate the innate and adaptive immune systems. Evidence demonstrates that pathogens directly and indirectly induce AD pathology, including amyloid-β (Aβ) accumulation, phosphorylation of tau protein, neuronal injury, and apoptosis. Chronic brain infection with HSV-1, Chlamydophila pneumoniae, and spirochetes results in complex processes that interact to cause a vicious cycle of uncontrolled neuroinflammation and neurodegeneration. Infections such as Cytomegalovirus, Helicobacter pylori, and periodontal pathogens induce production of systemic pro-inflammatory cytokines that may cross the blood-brain barrier to promote neurodegeneration. Pathogen-induced inflammation and central nervous system accumulation of Aβ damages the blood-brain barrier, which contributes to the pathophysiology of AD. Apolipoprotein E4 (ApoE4) enhances brain infiltration by pathogens including HSV-1 and Chlamydophila pneumoniae. ApoE4 is also associated with an increased pro-inflammatory response by the immune system. Potential antimicrobial treatments for AD are discussed, including the rationale for antiviral and antibiotic clinical trials.Item Novel regulation of neuronal genes implicated in Alzheimer disease by microRNA(2013-12-11) Long, Justin M.; Zhou, Feng C.; Lahiri, Debomoy K.; Farlow, Martin R.; Nass, Richard M.; Du, YanshengAlzheimer disease (AD) results, in part, from the excess accumulation of the amyloid-β peptide (Aβ) as neuritic plaques in the brain. The short Aβ peptide is derived from a large transmembrane precursor protein, APP. Two different proteolytic enzymes, BACE1 and the gamma-secretase complex, are responsible for cleaving Aβ peptide from APP through an intricate processing pathway. Dysregulation of APP and BACE1 levels leading to excess Aβ deposition has been implicated in various forms of AD. Thus, a major goal in this dissertation was to discover novel regulatory pathways that control APP and BACE1 expression as a means to identify novel drug targets central to the Aβ-generating process. MicroRNAs (miRNA) are short, non-coding RNAs that act as post-transcriptional regulators of gene expression through specific interactions with target mRNAs. Global analyses predict that over sixty percent of human transcripts contain evolutionarily conserved miRNA target sites. Therefore, the specific hypothesis tested was that miRNA are relevant regulators of APP and BACE1 expression. In this work, several specific miRNA were identified that regulate APP protein expression (miR-101, miR-153 and miR-346) or BACE1 expression (miR-339-5p). These miRNAs mediated their post-transcriptional effects via interactions with specific target sites in the APP and BACE1 transcripts. Importantly, these miRNA also altered secretion of Aβ peptides in primary human fetal brain cultures. Surprisingly, miR-346 stimulated APP expression via target sites in the APP 5’-UTR. The mechanism of this effect appears to involve other RNA-binding proteins that bind to the APP 5’-UTR. Expression analyses demonstrated that these miRNAs are expressed to varying degrees in the human brain. Notably, miR-101, miR-153 and miR-339-5p are dysregulated in the AD brain at various stages of the disease. The work in this dissertation supports the hypothesis that miRNAs are important regulators of APP and BACE1 expression and are capable of altering Aβ homeostasis. Therefore, these miRNA may possibly serve as novel therapeutic targets for AD.Item Semi-Quantitative Models for Identifying Potent and Selective Transthyretin Amyloidogenesis Inhibitors(Elsevier, 2017) Connelly, Stephen; Mortenson, David E.; Choi, Sungwook; Wilson, Ian A.; Powers, Evan T.; Kelly, Jeffery W.; Johnson, Steven M.; Department of Biochemistry & Molecular Biology, IU School of MedicineRate-limiting dissociation of the tetrameric protein transthyretin (TTR), followed by monomer misfolding and misassembly, appears to cause degenerative diseases in humans known as the transthyretin amyloidoses, based on human genetic, biochemical and pharmacologic evidence. Small molecules that bind to the generally unoccupied thyroxine binding pockets in the native TTR tetramer kinetically stabilize the tetramer, slowing subunit dissociation proportional to the extent that the molecules stabilize the native state over the dissociative transition state—thereby inhibiting amyloidogenesis. Herein, we use previously reported structure-activity relationship data to develop two semi-quantitative algorithms for identifying the structures of potent and selective transthyretin kinetic stabilizers/amyloidogenesis inhibitors. The viability of these prediction algorithms, in particular the more robust in silico docking model, is perhaps best validated by the clinical success of tafamidis, the first-in-class drug approved in Europe, Japan, South America, and elsewhere for treating transthyretin aggregation-associated familial amyloid polyneuropathy. Tafamidis is also being evaluated in a fully-enrolled placebo-controlled clinical trial for its efficacy against TTR cardiomyopathy. These prediction algorithms will be useful for identifying second generation TTR kinetic stabilizers, should these be needed to ameliorate the central nervous system or ophthalmologic pathology caused by TTR aggregation in organs not accessed by oral tafamidis administration.