Faculty Bibliography

The diagnosis of Parkinson's disease (PD) and atypical parkinsonian syndromes is difficult due to the lack of reliable, easily accessible biomarkers. Multiple system atrophy (MSA) is a synucleinopathy whose symptoms often overlap with PD. Exosomes isolated from blood by immunoprecipitation using CNS markers provide a window into the brain's biochemistry and may assist in distinguishing between PD and MSA. Thus, we asked whether α-synuclein (α-syn) in such exosomes could distinguish among healthy individuals, patients with PD, and patients with MSA. We isolated exosomes from the serum or plasma of these three groups by immunoprecipitation using neuronal and oligodendroglial markers in two independent cohorts and measured α-syn in these exosomes using an electrochemiluminescence ELISA. In both cohorts, α-syn concentrations were significantly lower in the control group and significantly higher in the MSA group compared to the PD group. The ratio between α-syn concentrations in putative oligodendroglial exosomes compared to putative neuronal exosomes was a particularly sensitive biomarker for distinguishing between PD and MSA. Combining this ratio with the α-syn concentration itself and the total exosome concentration, a multinomial logistic model trained on the discovery cohort separated PD from MSA with an AUC = 0.902, corresponding to 89.8% sensitivity and 86.0% specificity when applied to the independent validation cohort. The data demonstrate that a minimally invasive blood test measuring α-syn in blood exosomes immunoprecipitated using CNS markers can distinguish between patients with PD and patients with MSA with high sensitivity and specificity. Future optimization and validation of the data by other groups would allow this strategy to become a viable diagnostic test for synucleinopathies.

BACKGROUND:Assays that specifically measure α-synuclein seeding activity in biological fluids could revolutionize the diagnosis of Parkinson's disease. Recent improvements in α-synuclein real-time quaking-induced conversion assays of cerebrospinal fluid have dramatically reduced reaction times from 5-13 days down to 1-2 days. OBJECTIVE:To test our improved assay against a panel of cerebrospinal fluid specimens from patients with Parkinson's disease and healthy controls from the MJ Fox Foundation/NINDS BioFIND collection. METHODS:Specimens collected from healthy controls and patients with clinically typical moderate-to-advanced Parkinson's disease were tested without prior knowledge of disease status. Correlative analyses between assay parameters and clinical measures were performed by an independent investigator. RESULTS:BioFIND samples gave positive signals in 105/108 (97%) Parkinson's disease cases versus 11/85 (13%) healthy controls. Receiver operating characteristic analyses of diagnosis of cases versus healthy controls gave areas under the curve of 95%. Beyond binary positive/negative determinations, only weak correlations were observed between various assay response parameters and Parkinson's disease clinical measures or other cerebrospinal fluid analytes. Of note, REM sleep behavioral disorder questionnaire scores correlated with the reaction times needed to reach 50% maximum fluorescence. Maximum fluorescence was inversely correlated with Unified Parkinson's Disease Rating Scale motor scores, which was driven by the patients without REM sleep behavioral disorder. CONCLUSIONS:Our improved α-synuclein seed amplification assay dramatically reduces the time needed to diagnose Parkinson's disease while maintaining the high-performance standards associated with previous α-synuclein seed assays, supporting the clinical utility of this assay for Parkinson's disease diagnosis.

Several COVID-19 vaccines have recently been approved for emergency use according to governmental immunization programs. The arrival of these vaccines has created hope for people with Parkinson's disease (PD), as this can help to mitigate their risk of becoming infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which can lead to serious, life-threatening disease, at least among those with more advanced PD. However, both persons with PD and physicians looking after these individuals have expressed concerns about the vaccine's efficacy and safety in the specific context of PD and its symptomatic treatment. Here, we discuss our perspective on these concerns, based on our interpretation of the literature plus the unfolding experience with widespread vaccination in the population at large. Because the benefits and risks of COVID-19 vaccines do not appear to be different than in the general population, we recommend COVID-19 vaccination with approved vaccines to persons with PD, unless there is a specific contraindication. Some caution seems warranted in very frail and terminally ill elderly persons with PD living in long-term care facilities.

BACKGROUND:Leucine-rich repeat kinase 2 kinase inhibitors are being vigorously pursued as potential therapeutic options; however, there is a critical need for sensitive and quantitative assays of leucine-rich repeat kinase 2 function and target engagement. OBJECTIVES/OBJECTIVE:Our objective was to compare collection and storage protocols for peripheral blood mononuclear cells, and to determine the optimal conditions for downstream analyses of leucine-rich repeat kinase 2 in PD cohorts. METHODS:Here, we describe enzyme-linked immunosorbent assay-based assays capable of detecting multiple aspects of leucine-rich repeat kinase 2 function at endogenous levels in human tissues. RESULTS:In peripheral blood mononuclear cells from both healthy and affected carriers of the G2019S mutation in leucine-rich repeat kinase 2, we report, for the first time, significantly elevated in vitro kinase activity, while detecting a significant increase in pS935/leucine-rich repeat kinase 2 in idiopathic PD patients. CONCLUSIONS:Quantitative assays such as these described here could potentially uncover specific markers of leucine-rich repeat kinase 2 function that are predictive of disease progression, aid in patient stratification, and be a critical component of upcoming clinical trials. © 2020 International Parkinson and Movement Disorder Society.

Objective: To determine whether newly diagnosed Parkinson's disease (PD) patients with REM sleep behavior disorder (RBD) are more likely to have symptoms of autonomic dysfunction.
Background(s): RBD is highly associated with development of asynucleinopathies but only 51% of PD patients have RBD1,2. We addressed whether PD with and without RBD have different clinical phenotypes and progression.
Method(s): Hypothesis driven analysis of 295 early stage PD patients within 2 years from diagnosis on no PD medications from the Parkinson's Progressive Marker Initiative (PPMI) cohort were obtained. Genetic, SWEED and prodromal subgroups were excluded from analysis. RBDSQ equal or greater than 1 for item 6 (q6) was used to identify patients with RBD as this cutoff has greater sensitivity and specificity for identifying true RBD in PD3,4 Results: Subjects from baseline visit were divided in RBD+ (RBDSQ q6>1, n=128) and RBD- (RBDSQ q6<1, n=167). We considered SCOPA subscores (gastrointestinal(GI), urinary(UR), thermoregulation(THERM), cardiovascular(CV), pupillomotor(PM), sex(SEX)), sense of smell (UPSIT), anxiety (STAIT-trait), depression (GDS), motor (updrs-part3) and cognitive function (MOCA), UPDRS total score. Shapiro-Wilk and Mann-Whitney test for non-parametric data were used for the analyses. SCOPA sub-scores for the majority of the autonomic symptoms (GI, THERM, CV, PM) but not UR and SEX, were significantly higher in the REM+ cohort (p=<0.005). The other traits did not show statistically significant differences. Statistical significance between the two groups for GI, THERM, CV remained consistent using other thresholds for differentiating REM+ vs REM- groups (RBDSQ total score greater than 5 or combined RBDSQ total score and q6).
Conclusion(s): Our hypothesis driven analyses show that early stage PD patients with RBD have greater prevalence of autonomic symptoms, without worse UPDRS motor scores. This suggests that brainstem and peripheral autonomic symptoms cluster together, but are not associated with more diffuse involvement of motor systems and cognitive impairment at this early stage of PD. Prior analyses of PPMI data have identified a "diffuse/ malignant" subtype associated with higher UPDRS motor score, RBDSQ score, autonomic symptoms (SCOPA-AUT) and worse cognitive impairment5.6. These differences might be accounted by our more stringent criteria for RBD or our statistical approach using specific hypothesis versus cluster driven analyses

Although macroautophagy/autophagy deficiency causes degenerative diseases, the deletion of essential autophagy genes in adipocytes paradoxically reduces body weight. Brown adipose tissue (BAT) plays an important role in body weight regulation and metabolic control. However, the key cellular mechanisms that maintain BAT function remain poorly understood. in this study, we showed that global or brown adipocyte-specific deletion of pink1, a Parkinson disease-related gene involved in selective mitochondrial autophagy (mitophagy), induced BAT dysfunction, and obesity-prone type in mice. Defective mitochondrial function is among the upstream signals that activate the NLRP3 inflammasome. NLRP3 was induced in brown adipocyte precursors (BAPs) from pink1 knockout (KO) mice. Unexpectedly, NLRP3 induction did not induce canonical inflammasome activity. Instead, NLRP3 induction led to the differentiation of pink1 KO BAPs into white-like adipocytes by increasing the expression of white adipocyte-specific genes and repressing the expression of brown adipocyte-specific genes. nlrp3 deletion in pink1 knockout mice reversed BAT dysfunction. Conversely, adipose tissue-specific atg7 KO mice showed significantly lower expression of Nlrp3 in their BAT. Overall, our data suggest that the role of mitophagy is different from general autophagy in regulating adipose tissue and whole-body energy metabolism. Our results uncovered a new mitochondria-NLRP3 pathway that induces BAT dysfunction. The ability of the nlrp3 knockouts to rescue BAT dysfunction suggests the transcriptional function of NLRP3 as an unexpected, but a quite specific therapeutic target for obesity-related metabolic diseases.

BACKGROUND:Three motor phenotypes have been described in PD: postural instability and gait difficulty (PIGD) dominant, tremor-dominant (TD), and indeterminate (IND) subtype. These phenotypes have been associated with different cognitive trajectories, motor outcomes, and biomarkers profiles. However, whether motor subtype classifications change with treatment and disease progression is not well established. METHODS:To evaluate motor subtype ratio changes, we used the chi-square test for the off and on state motor subtypes for 115 PD participants in the BioFIND study and used repeated-measures analyses to evaluate longitudinal changes in 162 PD participants with five-year follow-up in the PPMI study. RESULTS:PIGD and TD subtypes in moderate to advanced PD participants change with dopaminergic agents. For those who shifted subtypes, improvement in tremor accounted for the transition of 15 (25.4%) TD participants, while the lack of tremor improvement along with minimal changes in PIGD score resulted in changes for eight (19.0%) PIGD individuals. Analyses of PPMI data revealed that all three subgroups had a significant decrease in subtype ratio with disease progression and a significant decline in subtype ratio occurred only in the TD subgroup with dopaminergic agents. The impact of dopaminergic medication effect on subtype shift for each visit was also more notable with disease advancement. CONCLUSIONS:Motor subtypes are not fixed but change with progression of the disease and with treatment. Improvement in tremor was the main contributor to motor phenotype transitions in the BioFIND cohort. A more stable classification system for subtypes based on underlying biological differences is desirable.