Christina Doriana Orru

A Test for Creutzfeldt–Jakob Disease Using Nasal Brushings

BACKGROUNDnDefinite diagnosis of sporadic Creutzfeldt-Jakob disease in living patients remains a challenge. A test that detects the specific marker for Creutzfeldt-Jakob disease, the prion protein (PrP(CJD)), by means of real-time quaking-induced conversion (RT-QuIC) testing of cerebrospinal fluid has a sensitivity of 80 to 90% for the diagnosis of sporadic Creutzfeldt-Jakob disease. We have assessed the accuracy of RT-QuIC analysis of nasal brushings from olfactory epithelium in diagnosing sporadic Creutzfeldt-Jakob disease in living patients.nnnMETHODSnWe collected olfactory epithelium brushings and cerebrospinal fluid samples from patients with and patients without sporadic Creutzfeldt-Jakob disease and tested them using RT-QuIC, an ultrasensitive, multiwell plate-based fluorescence assay involving PrP(CJD)-seeded polymerization of recombinant PrP into amyloid fibrils.nnnRESULTSnThe RT-QuIC assays seeded with nasal brushings were positive in 30 of 31 patients with Creutzfeldt-Jakob disease (15 of 15 with definite sporadic Creutzfeldt-Jakob disease, 13 of 14 with probable sporadic Creutzfeldt-Jakob disease, and 2 of 2 with inherited Creutzfeldt-Jakob disease) but were negative in 43 of 43 patients without Creutzfeldt-Jakob disease, indicating a sensitivity of 97% (95% confidence interval [CI], 82 to 100) and specificity of 100% (95% CI, 90 to 100) for the detection of Creutzfeldt-Jakob disease. By comparison, testing of cerebrospinal fluid samples from the same group of patients had a sensitivity of 77% (95% CI, 57 to 89) and a specificity of 100% (95% CI, 90 to 100). Nasal brushings elicited stronger and faster RT-QuIC responses than cerebrospinal fluid (P<0.001 for the between-group comparison of strength of response). Individual brushings contained approximately 10(5) to 10(7) prion seeds, at concentrations several logs10 greater than in cerebrospinal fluid.nnnCONCLUSIONSnIn this preliminary study, RT-QuIC testing of olfactory epithelium samples obtained from nasal brushings was accurate in diagnosing Creutzfeldt-Jakob disease and indicated substantial prion seeding activity lining the nasal vault. (Funded by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases and others.).

New generation QuIC assays for prion seeding activity

The ability of abnormal TSE-associated forms of PrP to seed the formation of amyloid fibrils from recombinant PrPSen has served as the basis for several relatively rapid and highly sensitive tests for prion diseases. These tests include rPrP-PMCA (rPMCA), standard quaking-induced conversion (S-QuIC), amyloid seeding assay (ASA), real-time QuIC (RT-QuIC) and enhanced QuIC (eQuIC). Here, we summarize recent improvements in the RT-QuIC-based assays that enhance the practicality, sensitivity and quantitative attributes of assays QuIC and promote the detection of prion seeding activity in dilute, inhibitor-laden fluids such as blood plasma.

Altered cholesterol ester cycle in skin fibroblasts from patients with Alzheimer's disease.

Intracellular cholesterol metabolism was reported to modulate amyloid-beta (Abeta) generation in Alzheimers disease (AD). Results presented herein demonstrated that, like brain cells, cultured skin fibroblasts from AD patients contained more cholesterol esters than fibroblasts from healthy subjects. Particularly, Oil Red-O, Nile Red, and filipin staining highlighted higher levels of neutral lipids which responded to inhibitors of acyl-coenzyme A:cholesterol acyl-transferase (ACAT-1), associated with an increase in free cholesterol. ACAT-1 mRNA levels increased significantly in AD fibroblasts, whereas those of sterol regulatory element binding protein-2, neutral cholesterol ester hydrolase, and ATP-binding cassette transporter member 1 were markedly down-regulated. Instead, mRNA levels of low-density lipoprotein receptor, hydroxy-methyl-glutaryl-coenzyme A reductase, caveolin-1, and amyloid-beta protein precursor (AbetaPP) were virtually unchanged. Notably, mRNA levels of both beta-site AbetaPP-cleaving enzyme 1 (BACE1) and neprilysin were significantly down-regulated. An increase in Abeta(40) and Abeta(42) immunostaining and a decrease in BACE1 active form were also found in AD versus control fibroblasts. Altogether, these findings support the hypothesis that the derangement of cholesterol homeostasis is a systemic alteration involving central but also peripheral cells of AD patients, and point to cholesterol ester levels in AD fibroblasts as an additional metabolic hallmark useful in the laboratory and clinical practice.

Antiprion Activity of Cholesterol Esterification Modulators: a Comparative Study Using Ex Vivo Sheep Fibroblasts and Lymphocytes and Mouse Neuroblastoma Cell Lines

ABSTRACT Our studies on the role of cholesterol homeostasis in the pathogenesis of scrapie revealed abnormal accumulation of cholesterol esters in ex vivo peripheral blood mononuclear cells (PBMCs) and skin fibroblasts from healthy and scrapie-affected sheep carrying a scrapie-susceptible genotype compared to sheep with a resistant genotype. Similar alterations were observed in mouse neuroblastoma N2a cell lines persistently infected with mouse-adapted 22L and RML strains of scrapie that showed up to threefold-higher cholesterol ester levels than parental N2a cells. We now report that proteinase K-resistant prion protein (PrPres)-producing cell populations of subclones from scrapie-infected cell lines were characterized by higher cholesterol ester levels than clone populations not producing PrPres. Treatments with a number of drugs known to interfere with different steps of cholesterol metabolism strongly reduced the accumulation of cholesterol esters in ex vivo PBMCs and skin fibroblasts from scrapie-affected sheep but had significantly less or no effect in their respective scrapie-resistant or uninfected counterparts. In scrapie-infected N2a cells, inhibition of cholesterol esters was associated with selective antiprion activity. Effective antiprion concentrations of cholesterol modulators (50% effective concentration [EC50] range, 1.4 to 40 μM) were comparable to those of antiprion reference compounds (EC50 range, 0.6 to 10 μM). These data confirm our hypothesis that abnormal accumulation of cholesterol esters may represent a biological marker of susceptibility to prion infection/replication and a novel molecular target of potential clinical importance.

Correction: Bank Vole Prion Protein As an Apparently Universal Substrate for RT-QuIC-Based Detection and Discrimination of Prion Strains

The following information is missing from the Funding section: BG is supported by NIH P30 AG10133.

In vitro synergistic anti-prion effect of cholesterol ester modulators in combination with chlorpromazine and quinacrine

Our studies on the role of cholesterol in prion infection/replication showed that brains and peripheral cells of sheep susceptible-to or suffering-from Scrapie were characterized by an altered cholesterol homeostasis, and that drugs affecting cholesterol ester pool were endowed with selective anti-prion activity in N2a cell lines infected with the 22L and RML prion strains. In these prion-infected N2a cell lines, we now report increased anti-prion activity of dual-drug combinations consisting of cholesterol ester modulators associated with prion inhibitors. Synergism was obtained with the cholesterol ester modulators everolimus, pioglitazone, progesterone, and verapamil associated with the anti-prion chlorpromazine, and with everolimus and pioglitazone associated with the anti-prion quinacrine. In addition, comparative lipid analyses in prion-infected vs. uninfected N2a cells, demonstrated a derangement of type and distribution of cholesterol ester, free cholesterol, and triglyceride pools in the infected cells. Single-drug treatments differently affected synthesis of the various lipid forms, whereas combined drug treatments appeared to restore a lipid profile similar to that of the untreated-uninfected cells. We conclude that the anti-prion synergistic effects of cholesterol ester modulators associated with the cholesterol-interfering anti-prion drugs chlorpromazine and quinacrine may arise from the ability of combined drugs to re-establish lipid homeostasis in the prion-infected cells. Overall, these data suggest that inhibition of prion replication can be readily potentiated by combinatorial drug treatments and that steps of cholesterol/cholesterol ester metabolism may represent suitable targets.

Ultrasensitive RT-QuIC Seed Amplification Assays for Disease-Associated Tau, α-Synuclein, and Prion Aggregates

The abnormal assembly of tau, α-synuclein (αSyn), or prion protein into oligomers and multimers underpins the molecular pathogenesis of multiple neurodegenerative diseases. Such pathological aggregates can often grow by seeded polymerization mechanisms. We and others have taken advantage of these mechanisms to amplify seeding activities in vitro and devise ultrasensitive, specific and quantitative assays for these etiological biomarkers. Real-time quaking-induced conversion (RT-QuIC) assays are performed in multiwell plates with fluorescent readouts, facilitating efficient throughput. Prion RT-QuIC assays on cerebrospinal fluid (CSF) samples are being widely used for antemortem diagnosis of human prion diseases. Recently, we have also described a tau RT-QuIC prototype that has been optimized for Pick disease (with predominant 3R tau pathology) that detects 3R tau seeds in postmortem CSF, and brain tissue dilutions as extreme as a billion-fold. αSyn RT-QuIC prototypes have also been developed, providing ~92% diagnostic sensitivity and 100% specificity for Parkinsons disease and dementia with Lewy bodies using antemortem CSF. Here we provide detailed protocols for our 3R tau and αSyn RT-QuIC assays and refer the reader to published up-to-date protocols for prion RT-QuIC assays (Orru et al. Methods Mol Biol 1658:185-203, 2017; Schmitz et al. Nat Protoc 11:2233-2242, 2016).

RAPID AND ULTRA-SENSITIVE DETECTION OF α-SYNUCLEIN SEEDS IN BRAIN AND CEREBROSPINAL FLUID BY α-SYN RT-QUIC: AN AID TO DIAGNOSIS FOR PD AND DLB

total of 38 adults (mean age1⁄4 69.36 years) with well-established risk factors forADwere recruited. Florbetapir amyloid PET scanswere obtained andneocortical PETstandardizeduptakevalue ratios (SUVr) for six regions were summed and normalized to thewhole cerebellum. An SUVr threshold of 1.1 or greater was used to identify preclinical AD subjects. OCTA images were captured using Optovue AngioVue 3x 3-volume scans centered on the fovea (Optovue, Fremont, CA, USA). The Df was measured in linearized superficial microvascular plexus images in order to measure the space-filling linear extension of the large vessels, retaining only vessels with a diameter of more or equal to 25 mm. Results:For each participant the Df (with a grid size of 64 pixels) was obtained for the right eye retina, and the mean and standard deviation (SD) of measurements for the two groups were computed. The mean Df for preclinical AD subjects (N 1⁄4 10) was significantly lower (r1⁄40.005) (Figure 1), with substantially greater variability, than that for healthy controls (N1⁄4 28) (heteroscedastic Student’s t-test, 2-tailed).Conclusions:Ourfindings suggest that individuals at high-risk for preclinical AD (Figure 2) have less density and complexityof retinalmicrovascularnetworks in the superficial vascular plexus than healthy controls (Figure 3). Retinal vascular distribution and blood flow are already altered during the earliest stages of AD.

Prion Biochemistry and Therapeutics

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are caused by infectious agents that are unusually hard to decontaminate and can resist more heat and radiation than other pathogens. These characteristics led to proposals, during the 1960s, that they might lack nucleic-acid genomes. The first recognized TSE disease was scrapie, a widespread infection of sheep that can persist in pastures for years after removal of infected animals. Similarities between scrapie and human kuru, which was spread by cannibalistic mortuary feasts amongst the Fore tribe in Papua New Guinea, contributed to widespread interest in these fatal neurodegenerative diseases. Since then, the impact of TSEs has been greatly amplified by the recognition of more common human forms, such as Creutzfelt-Jakob disease (CJD), and the epidemics of bovine spongiform encephalopathy (BSE) and cervid chronic-wasting disease (CWD).

Pharmacologic Cholesterol Homeostasis Affects Prion Generation in a Synergistic Manner

It is generally recognised that prion replication in the brain is associated with cholesterol changes. We now show that prion diseases are likely associated with systemic metabolic alterations that involve changes both in the content and distribution of the different pools of cellular cholesterol, free cholesterol and cholesterol esters, as well as of other cellular lipids, including phospholipids and triglycerides. The synergic anti-prion effect showed by drug combinations affecting cholesterol metabolism at different levels suggest that pharmacologic interventions restoring lipid homeostasis may represent a more successful therapeutic approach than drug treatments lowering cholesterol content per se (i.e. statins). Notably, our data also point to neutral lipid accumulation in peripheral cells as an easy-to-detect hallmark associated with disease and/or indicative of increased susceptibility to develop disease following infection.