Abstract Body

Intrathecal (ITH) drug dosing into the cerebrospinal fluid (CSF) is increasingly used to bypass the blood-brain barrier (BBB) for the delivery of small molecules, biologics, oligonucleotides, gene therapy vectors, exosomes, and cell therapies to the central nervous system (CNS). Knowledge gaps still remain for optimizing target engagement with various drug modalities using this dosing route. Some of the anatomical features and physiological functions of the ITH compartment, which impact drug pharmacokinetics (PK), are also emerging as important determinants of endogenous CNS waste clearance and immune surveillance functions. This presentation will share insights from multimodal imaging data (MRI, PET, SPECT, fluorescence, histology) obtained with ITH-dosed molecular probes representing multiple endogenous and therapeutic molecular classes including small molecules, proteins, antisense oligonucleotides, and nanoparticles. Rodent, non-human primate, and clinical studies using imaging-based PK and target engagement determination of ITH-dosed molecules will be presented. Multimodal imaging data to be presented will highlight some molecular features that influence the relative CNS entry, peripheral clearance, and immune surveillance routing of molecular entities from the ITH space. Collectively, the presented studies will elucidate the relative roles of molecular features, neuraxial ITH anatomy, CSF convection, perivascular biology, and immune surveillance functions in determining intrathecal molecular disposition. This knowledge is relevant for improving the design of ITH therapeutic interventions as well as for a better understanding of ITH biology that may contribute to the pathogenesis of neurodegenerative and neuroinflammatory diseases.

Aims

The sense of smell is orchestrated by the olfactory mucosa in the upper nasal cavity. Cells of the olfactory mucosa are known to be altered in certain neurodegenerative conditions but have not been well characterized in Alzheimer’s Disease. This is surprising given that loss of olfaction is one of the earliest symptoms of the disease. Here we report the use of olfactory mucosa cells obtained from living biopsy donors as a research model for Alzheimer’s Disease.

Methods

For the first time we have applied single-cell RNA sequencing of olfactory mucosa cells obtained from cognitively normal individuals and persons with Alzheimer’s Disease to provide subtle delineation of cellular heterogeneity in olfactory mucosa cells, revealing the existence of potential markers and key factors contributing to the disease.

Results

The single-cell RNA sequencing approach elucidated the cellular makeup of individual olfactory mucosa cells. It uncovered a total of 1766 annotated genes, of which 136 were differentially expressed in persons with Alzheimer’s Disease. 62 % of the altered genes were up regulated while the expression of 38 % of the genes were reduced in persons with Alzheimer’s Disease compared to cognitively normal individuals. Functional testing of beta-amyloid production revealed distinct alterations of the cells derived from persons with Alzheimer’s Disease as the levels of tau protein and secreted cytokines were unaltered between the study groups.

Conclusions

Taken together, our results support the utilization of olfactory mucosa cells as a research model, which holds promise for detailed understanding of disease mechanisms and discovery of biomarkers for Alzheimer’s Disease.

Aims

Pathological comorbidity is increasingly recognized in the field of aging and dementia. We are starting to disentangle biological similarities and differences between the two most prevalent dementias: Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB). In the current work, we present the latest discoveries on the association between biomarkers of AD and cerebrovascular disease, neurodegeneration, and clinical phenotype in atypical AD and DLB.

Methods

We used data from several international studies. Atypical AD was based on neuroimaging or postmortem data. Biomarkers were assessed on neuroimaging and cerebrospinal fluid.

Results

Among atypical AD subtypes (around 50% of AD patients), hippocampal-sparing AD shared important similarities with DLB. We found that both hippocampal-sparing AD and DLB patients were younger, included more males, were more highly educated, had lower frequency of the APOE epsilon-4 allele, and had younger disease onset than the other AD subtypes, including typical AD. Hippocampal-sparing AD had a high frequency of Lewy body pathology. Further, hippocampal-sparing was the most common pattern of brain atrophy in DLB. Both hippocampal-sparing AD and DLB had increased cerebrovascular disease in parietal/occipital brain areas. Clinical phenotype was influenced by the spatial distribution of biomarkers of AD and cerebrovascular disease and neurodegeneration, both in AD and DLB.

Conclusions

Hippocampal-sparing AD, an atypical form of AD, may share pathophysiological mechanisms with DLB. Advancing our current knowledge about the biological heterogeneity underlying dementia will help to improve diagnosis and prognosis, as well as to increase the chance of success of future clinical trials.

Aims

The present study aimed i) to survey the prevalence of prodromal symptoms of Lewy body disease (LBD) in Japanese health checkup examinees, for identifying at-risk subjects, ii) to clarify clinical features and natural history of such at-risk subjects.

Methods

We conducted a survey of prodromal symptoms in healthy individuals using the following self-reported questionnaires: the Scale for Outcomes in Parkinson’s disease for Autonomic Symptoms (SCOPA-AUT); Self-administered Odor Question (SAOQ); REM Sleep Behavior Disorder Screening Scale (RBDSQ); Beck Depression Inventory-Second Edition (BDI-II); Epworth Sleepiness Scale (ESS); and Physical Activity Scale for the Elderly (PASE). Subjects ≥50 years of age with ≥2 core prodromal symptoms (dysautonomia, hyposmia, and RBD), were classified as at-risk. We conducted a detailed analysis with MIBG scintigraphy and DaT SPECT for these at-risk subjects.

Results

A total of 4,953 out of 12,378 (40.0%) participants completed all the questionnaires. Among 2,726 subjects ≥50 years of age, 155 (5.7%) were classified as at-risk. These subjects also had worse scores of questionnaires about depression and daytime sleepiness. Nineteen out of 55 at-risk subjects (34.5%) had a deficit in either MIBG scintigraphy or DaT SPECT, even though they had no motor or cognitive decline.

Conclusions

Approximately 6% of the population aged 50 years or older had ≥2 prodromal symptoms, and about one-third of them had a deficit in either MIBG scintigraphy or DaT SPECT. From January 2021, we will conduct a preventive clinical trial of zonisamide for these at-risk subjects.

Aims

An assay kit for plasma NFL utilizing immunomagnetic reduction (IMR) was developed. The preclinical properties, such as the standard curve, limit of detection (LoD), and dynamic range, were characterized.

Methods

Thirty-one normal controls (NC), fifty-two patients with Parkinson’s disease (PD) or PD dementia (PDD) and thirty-one patients with Alzheimer’s disease (AD) were enrolled in the study. T-tests and receiver operating characteristic (ROC) curve analysis were performed to investigate the capability for discrimination among the clinical groups according to plasma NFL levels.

Results

The LoD of the NFL assay using the IMR kit was found to be 0.18 fg/ml. The dynamic range of the NFL assay reached 1000 pg/ml. The NC group showed a plasma NFL level of 7.70 ± 4.00 pg/ml, which is significantly lower than that of the PD/PDD (15.85 ± 7.82 pg/ml, p < 0.001) and AD (19.24 ± 8.99 pg/ml, p < 0.001) groups. A significant difference in plasma NFL levels was determined between the PD and AD groups (p < 0.01). The cut-off value of the plasma NFL concentration for differentiating NCs from dementia patients was found to be 12.71 pg/ml, with a clinical sensitivity and specificity of 73.5% and 90.3%, respectively. The AUC was 0.868. Furthermore, the cut-off value of the plasma NFL concentration for discriminating AD from PD/PDD was found to be 18.02 pg/ml, with a clinical sensitivity and specificity of 61.3% and 65.4%, respectively. The AUC was 0.630.

Conclusions

Clear differences in plasma NFL concentrations were observed among NCs and PD and AD patients.

Aims

Neurofilament light Chain (NfL) is a biomarker for neuroaxonal damage. We assessed, whether NfL levels are correlated to the functional integrity of presynaptic dopamine neurons. We correlated NfL levels and other biomarkers in the CSF with the results of dopamine transporter (DAT) imaging, which visualizes the loss of presynaptic DAT.

Methods

We retrospectively identified 47 patients (17 Alzheimer Dementia, 10 idiopathic Parkinson Disease, 7 Lewy Body Dementia, 13 Progressive supranuclear palsy or Corticobasal syndrome) who received DAT imaging and lumbar puncture. DAT imaging was performed according to current guidelines and Z-scores indicating the decrease in uptake compared to a normal collective were calculated for the Nucl. caudatus and Putamen of each side. CSF biomarkers Progranulin (PGRN), Total Tau (T-Tau), Alpha-Synuclein (aSyn), phosphorylated Neurofilament heavy Chain (pNfH) and NfL were correlated with the Z-scores.

Results

DAT imaging results in AD patients did not correlate with any biomarker. Subsuming all movement disorders with nigrostriatal neurodegeneration resulted in a strong correlation between DAT imaging results and NfL (Ncl caudatus right p<0.01, left p<0.05, Putamen right p<0.05, left p<0.05) and between pNfH and Putamen (right p<0.05; left p<0.042). Progranulin, aSyn and T-Tau did not correlate with DAT imaging. Subdividing in disease cohorts did not reveal significant correlations.

Conclusions

We show for the first time a strong correlation of NfL and pNfH with a pathological change in presynaptic DAT density in movement disorders. This indicates that axonal dopaminergic neurodegeneration is aligned with the neurodegenerative process in movement disorders but not in Alzheimer’s disease.

Aims

To assess the relationship between amyloid β (Aβ), substantia nigra (SN) atrophy, dopamine transporter (DAT) striatal activity, and white matter hyperintensities (WMH) and the risk of future freezing of gait (FOG) in de novo Parkinson’s disease (PD) patients.

Methods

We studied 423 participants from from the Parkinson’s Progression Markers Initiative (PPMI). Deformation based morphometry from anatomical MRI was used to measure SN atrophy. WMH load on MRI was used as a measure of white matter pathology. Cerebrospinal fluid (CSF) Aβ, putamen and caudate SPECT-based DAT levels were also obtained. Future FOG was evaluated using MDS-UPDRS items 2.13 and 3.11, defined as whether the score for either item was ≥ 1 at any follow-up visit. We investigated whether WMH burden mediates the impact of Aβ on future FOG, controlling for age, sex, SN atrophy, and DAT activity.

Results

Baseline SN atrophy, WMH load, Aβ, putamen and caudate DAT levels were significantly different between PD patients with and without future FOG (p < 0.008, Figure 1).

The effect of Aβ on future FOG was fully mediated via WMH burden, independent of either SN atrophy or DAT levels (average causal mediation effect: ab = - 0.013, p = 0.02; average direct effect: C' = -0.053, p = 0.053, Figure 2).

Conclusions

Baseline Aβ impacts future FOG in PD patients through an increase in WMH burden, in a pathway independent of Lewy body pathology as measured by SN atrophy and striatal DAT activity.

Aims

Despite numerous attempts to develop preclinical diagnosis of Parkinson’s disease (PD) based on searching premotor symptoms or biomarkers in body fluids, there is no technology recommended for clinical use. Indeed, all detected markers are not specific. This study aimed to develop a fundamentally new approach to preclinical diagnosis of PD based on a provocative test, which is widely used in internal medicine for diagnosis of chronic diseases.

Methods

MPTP was administered to mice for modeling preclinical stage of PD. In two weeks, mice received provocative agent – alpha-methyl-p-tyrosine (αMPT), a reversible inhibitor of tyrosine hydroxylase and dopamine synthesis.

Results

First, we used MPTP to model in mice preclinical PD with loss of striatal dopamine for 20% and 60%, but without motor disorders. Then, we selected a dose of αMPT, which causes the appearance of motor disorders in mice with minimal MPTP-induced loss of DA, but not in normal mice. This was due to a decrease of dopamine to 30%, the threshold for the onset of motor disorders in PD. Finally, we found the minimum doses of αMPT that, in mice with varying depletion of striatal dopamine, bring dopamine loss to a threshold at which motor disorders appear. This dose dependence can be used to estimate the degree of degradation of the nigrostriatal dopaminergic system in preclinical stage of PD.

Conclusions

This is the first attempt to develop a provocative test for preclinical diagnosis of PD, which can also be used to estimate the degradation of the nigrostriatal dopaminergic system.

Supported by Skolkovo Foundation.