LRRK2 G2019S variant is associated with transcriptional changes in Parkinson's disease human myeloid cells under proinflammatory environment.

The G2019S mutation in the leucine-rich repeat kinase 2 (LRRK2) gene is a major risk factor for the development of Parkinson's disease (PD). LRRK2, although ubiquitously expressed, is highly abundant in cells of the innate immune system. Given the importance of central and peripheral immune cells in the development of PD, we sought to investigate the consequences of the G2019S mutation on microglial and monocyte transcriptome and function. We have generated large-scale transcriptomic profiles of isogenic human induced microglial cells (iMGLs) and patient derived monocytes carrying the G2019S mutation under baseline culture conditions and following exposure to the proinflammatory factors IFNγ and LPS. We demonstrate that the G2019S mutation exerts a profound impact on the transcriptomic profile of these myeloid cells, and describe corresponding functional differences in iMGLs. The G2019S mutation led to an upregulation in lipid metabolism and phagolysosomal pathway genes in untreated and LPS/IFNγ stimulated iMGLs, which was accompanied by an increased phagocytic capacity of myelin debris. We also identified dysregulation of cell cycle genes, with a downregulation of the E2F4 regulon. Transcriptomic characterization of human-derived monocytes carrying the G2019S mutation confirmed alteration in lipid metabolism associated genes. Altogether, these findings reveal the influence of G2019S on the dysregulation of the myeloid cell transcriptome under proinflammatory conditions.

Differences in Sex-Specific Frequency of Glucocerebrosidase Variant Carriers and Familial Parkinsonism.

BACKGROUND: Although men and women with the LRRK2 G2019S variant appear to be equally likely to have Parkinson's disease (PD), the sex-distribution among glucocerebrosidase (GBA) variant carriers with PD, including limited to specific variant severities of GBA, is not well understood. Further, the sex-specific genetic contribution to PD without a known genetic variant is controversial. OBJECTIVES: To better understand sex differences in genetic contribution to PD, especially sex-specific frequencies among GBA variant carriers with PD (GBA PD) and LRRK2-G2019S variant carriers with PD (LRRK2 PD). METHODS: We assess differences in the sex-specific frequency in GBA PD, including in subsets of GBA variant severity, LRRK2 PD, and idiopathic PD in an Ashkenazi Jewish cohort with PD. Further, we expand prior work evaluating differences in family history of parkinsonism. RESULTS: Both idiopathic PD (267/420 men, 63.6%) (P < 0.001) and GBA PD overall (64/107, 59.8%) (P = 0.042) were more likely to be men, whereas no difference was seen in LRRK2 PD (50/99, 50.5%) and LRRK2/GBA PD (5/10, 50%). However, among GBA PD probands, severe variant carriers were more likely to be women (15/19 women, 79.0%) (P = 0.005), whereas mild variant carriers (44/70 men, 62.9%) (P = 0.039) and risk-variant carriers (15/17 men, 88.2%) (P = 0.001) were more likely to be men. CONCLUSIONS: Our study demonstrates that the male-sex predominance present in GBA PD overall was not consistent across GBA variant severities, and a female-sex predominance was present among severe GBA variant carriers. Therefore, research and trial designs for PD should consider sex-specific differences, including across GBA variant severities. © 2022 International Parkinson and Movement Disorder Society.

Association of Olfactory Performance With Motor Decline and Age at Onset in People With Parkinson Disease and the LRRK2 G2019S Variant.

BACKGROUND AND OBJECTIVES: There is clinical and phenotypic heterogeneity in LRRK2 G2019S Parkinson disease (PD), including loss of smell. Olfactory scores have defined subgroups of LRRK2 PD at baseline. We now extend this work longitudinally to better determine features associated with olfactory classes and to gain further insight into this heterogeneity. METHODS: Evaluation of 162 patients with LRRK2 PD and 198 patients with idiopathic PD (IPD) from the LRRK2 Ashkenazi Jewish Consortium was performed, with follow-up available for 92 patients with LRRK2 PD and 74 patients with IPD. Olfaction (University of Pennsylvania Smell Identification Test [UPSIT]), motor function (Unified Parkinson Disease Rating Scale), and cognition (Montreal Cognitive Assessment), as well as sleep, nonmotor, and mood, were measured. Gaussian mixture models were applied on the UPSIT percentile score to determine subgroups based on olfactory performance. Linear mixed effects models, using PD duration as the time scale, assessed the relationship between UPSIT subgroup membership and motor/cognitive change. RESULTS: Baseline olfaction was better in LRRK2 PD compared with IPD (mean UPSIT ± SD: 24.2 ± 8.8 vs 18.9 ± 7.6), with higher mean percentile scores (difference: 15.3 ± 11.6) (p < 0.001) and less frequent hyposmia (55.6% vs 85.4%; p < 0.001). Analysis suggested 3 classes among LRRK2 PD. Age at onset in LRRK2 PD was earlier in the worst olfaction group (group 1), compared with groups 2 and 3 (54.5 ± 11.1 vs 61.7 ± 9.3) (p = 0.012), and separately in the hyposmic group overall (55.0 ± 11.3 vs 61.7 ± 9.1) (p < 0.001). Longitudinal motor deterioration in LRRK2 PD was also significantly faster in the worst UPSIT group than the best UPSIT group (group 3 vs group 1: B = 0.31, SE = 0.35 vs B = 0.96, SE = 0.28) (rate difference = -0.65, SE = 0.29) (p = 0.03). However, olfactory group membership was not significantly associated with cognitive decline. DISCUSSION: In this large LRRK2 cohort with longitudinal analysis, we extend prior work demonstrating subgroups defined by olfaction in LRRK2 G2019S PD and show that the worst olfaction group has earlier age at PD onset and more rapid motor decline. This supports a subgroup of LRRK2 PD that might show more rapid change in a clinical trial of LRRK2-related agents and highlights the need to integrate careful phenotyping into allocation schema in clinical trials of LRRK2-related agents. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that worse olfactory scores were associated with an earlier age at symptomatic onset and a faster rate of motor deterioration in patients with LRRK2 PD.

Clinical profiles and outcomes of deep brain stimulation in G2019S LRRK2 Parkinson disease.

OBJECTIVE: The objective of this study was to evaluate clinical features and response to deep brain stimulation (DBS) in G2019S LRRK2-Parkinson disease (LRRK2-PD) and idiopathic PD (IPD). METHODS: The authors conducted a clinic-based cohort study of PD patients recruited from the Mount Sinai Beth Israel Genetics database of PD studies. The cohort included 87 participants with LRRK2-PD (13 who underwent DBS) and 14 DBS participants with IPD enrolled between 2009 and 2017. The baseline clinical features, including motor ratings and levodopa-equivalent daily dose (LEDD), were compared among LRRK2-PD patients with and without DBS, between LRRK2-PD with DBS and IPD with DBS, and between LRRK2-PD with subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) DBS. Longitudinal motor scores (Unified Parkinson's Disease Rating Scale-part III) and medication usage were also assessed pre- and postoperatively. RESULTS: Compared to LRRK2-PD without DBS (n = 74), the LRRK2-PD with DBS cohort (n = 13) had a significantly younger age of onset, longer disease duration, were more likely to have dyskinesia, and were less likely to experience hand tremor at disease onset. LRRK2-PD participants were also more likely to be referred for surgery because of severe dyskinesia (11/13 [85%] vs 6/14 [43%], p = 0.04) and were less likely to be referred for medically refractory tremor (0/13 [0%] vs 6/14 [43%], p = 0.02) than were IPD patients. Among LRRK2-PD patients, both STN-DBS and GPi-DBS targets were effective, although the sample size was small for both groups. There were no revisions or adverse effects reported in the GPi-DBS group, while 2 of the LRRK2-PD participants who underwent STN-DBS required revisions and a third reported depression as a stimulation-related side effect. Medication reduction favored the STN group. CONCLUSIONS: The LRRK2-PD cohort referred for DBS had a slightly different profile, including earlier age of onset and dyskinesia. Both the STN and GPi DBS targets were effective in symptom suppression. Patients with G2019S LRRK2 PD were well-suited for DBS therapy and had favorable motor outcomes regardless of the DBS target. LRRK2-DBS patients had longer disease durations and tended to have more dyskinesia. Dyskinesia commonly served as the trigger for DBS surgical candidacy. Medication-refractory tremor was not a common indication for surgery in the LRRK2 cohort.

An increased rate of longitudinal cognitive decline is observed in Parkinson's disease patients with low CSF Aß42 and an APOE ε4 allele.

OBJECTIVE: Low concentrations of cerebrospinal fluid (CSF) amyloid-beta (Aß-42) are associated with increased risk of cognitive decline in Parkinson's disease (PD). We sought to determine whether APOE genotype modifies the rate of cognitive decline in PD patients with low CSF Aß-42 compared to patients with normal levels. METHODS: The Parkinson's Progression Markers Initiative is a longitudinal, ongoing study of de novo PD participants, which includes APOE genotyping, CSF Aß-42 determinations, and neuropsychological assessments. We used linear mixed effects models in three PD groups (PD participants with low CSF Aß at baseline, PD participants with normal CSF Aß, and both groups combined). Having at least one copy of the APOE ɛ4 allele, time, and the interaction of APOE ɛ4 and time were predictor variables for cognitive change, adjusting for age, gender and education. RESULTS: 423 de novo PD participants were followed up to 5 years with annual cognitive assessments. 103 participants had low baseline CSF Aß-42 (39 APOE ε4+, 64 APOE ε4-). Compared to participants with normal CSF Aß-42, those with low CSF Aß-42 declined faster on most cognitive tests. Within the low CSF Aß-42 group, APOE ε4+ participants had faster rates of decline on the Montreal Cognitive Assessment (primary outcome; 0.57 points annual decline, p = .005; 5-year standardized change of 1.2) and the Symbol Digit Modalities Test (1.4 points annual decline, p = .002; 5-year standardized change of 0.72). DISCUSSION: PD patients with low CSF Aß-42 and APOE ε4+ showed a higher rate of cognitive decline early in the disease. Tests of global cognition (Montreal Cognitive Assessment) and processing speed (Symbol Digit Modalities Test) were the most sensitive to early cognitive decline. Results suggest that CSF Aß-42 and APOE ε4 might interact to promote early cognitive changes in PD patients.

Do CSF Biomarkers Predict Progression to Cognitive Impairment in Parkinson's disease patients? A Systematic Review.

Many patients with Parkinson's disease (PD) will develop cognitive impairment. Cross-sectional studies have shown that certain protein levels are altered in the cerebrospinal fluid (CSF) of PD patients with dementia and are thought to represent potential biomarkers of underlying pathogenesis. Recent studies suggest that CSF biomarker levels may be predictive of future risk of cognitive decline in non-demented PD patients. However, the strength of this evidence and difference between specific CSF biomarkers is not well delineated. We therefore performed a systematic review to assess if levels of specific CSF protein biomarkers are predictive of progression to cognitive impairment. Nine articles were identified that met inclusion criteria for the review. Findings from the review suggest a convergence of evidence that a low baseline Aß42 in the CSF of non-demented PD patients predicts development of cognitive impairment over time. Conversely, there is limited evidence that CSF levels of tau, either total tau or phosphorylated tau, is a useful predictive biomarker. There are mixed results for other CSF biomarkers such as α-synuclein, Neurofilament light chain, and Heart fatty acid-binding protein. Overall the results of this review show that certain CSF biomarkers have better predictive ability to identify PD patients who are at risk for developing cognitive impairment. Given the interest in developing disease-modifying therapies, identifying this group will be important for clinical trials as initiation of therapy prior to the onset of cognitive decline is likely to be more efficacious.

Peru's national folic acid fortification program and its effect on neural tube defects in Lima / Programa nacional del Perú de fortificación con ácido fólico y su efecto sobre los defectos del tubo neural en Lima

OBJECTIVE: To evaluate the impact of Peru's national folic acid fortification program on folic acid content in wheat flour, and the effect on birth prevalence of neural tube defects (NTDs) in Lima, and to compare the program's legislative requirements with international standards. METHODS: Bread was sampled from six sites across Peru and tested for folic acid. Data were obtained from the largest obstetric hospital in Lima on the prevalence of births (live and still) with NTDs during both the pre-fortification period (2004-2005) and post-fortification years (2007-2008). RESULTS: Folic acid content in the sampled bread met national legislative requirements but was less than one-half of the level recommended for Peru by the World Health Organization (WHO) (2.6 mg/kg wheat flour). Birth prevalence of NTDs was 18.4/10 000 in the pre-fortification period and 20.0/10 000 during post-fortification years. Relative risk for NTDs after fortification was 1.02 (95% confidence interval 0.77-1.35, P = 0.90). CONCLUSIONS: Peruvian legislative requirements for folic acid fortification are below international (WHO) recommendations; birth prevalence of NTDs in Lima is higher than international benchmarks; and no decrease in NTDs following fortification of flour with folic acid (according to Peruvian national standards) was observed. As increasing the level of folic acid in flour remains the most sustainable way of preventing NTDs, it is recommended that Peru increase its folic acid fortification requirements to meet those recommended by WHO (2.6 mg/kg).

OBJETIVO: Evaluar la repercusión que el programa nacional del Perú de fortificación con ácido fólico tiene en el contenido de ácido fólico de la harina de trigo y en la prevalencia de nacimientos de niños con defectos del tubo neural en Lima, así como comparar los requisitos legislativos del programa con las normas internacionales. MÉTODOS: Se hizo un muestreo del pan en seis zonas de Perú y se analizó su contenido de ácido fólico. Se obtuvieron datos del mayor hospital obstétrico de Lima referentes a la prevalencia de nacimientos de niños vivos o mortinatos con defectos del tubo neural durante el período anterior a la fortificación (2004-2005) y el posterior a la misma (2007-2008). RESULTADOS: El contenido de ácido fólico en las muestras de pan obtenidas satisfizo los requisitos legislativos nacionales, si bien fue inferior a la mitad de la concentración que la Organización Mundial de la Salud (OMS) recomienda para el Perú (2,6 mg/kg de harina de trigo). La prevalencia de nacimientos de niños con defectos del tubo neural fue de 18,4/10 000 en el período anterior a la fortificación y de 20,0/10 000 en los años posteriores a la fortificación. El riesgo relativo de los defectos del tubo neural después de la fortificación fue de 1,02 (intervalo de confianza de 95%: 0,77-1,35; P = 0,90). CONCLUSIONES: Los valores que la legislación peruana exige en lo que respecta a la fortificación con ácido fólico son inferiores a los que se recomiendan internacionalmente (OMS). La prevalencia de nacimientos de niños con defectos del tubo neural en Lima es superior a las cifras de referencia internacionales. Por otra parte, no se observó ninguna disminución de los defectos del tubo neural después de fortificar la harina con ácido fólico (según los valores normalizados nacionales peruanos). Dado que el aumento de la concentración de ácido fólico en la harina sigue siendo la manera más sostenible de prevenir los defectos del tubo neural, se recomienda que el Perú haga más estrictos los requisitos relativos a la fortificación con ácido fólico para ajustarse a los valores recomendados por la OMS (2,6 mg/kg).

Effects of translocator protein (18 kDa) ligands on microglial activation and neuronal death in the quinolinic-acid-injected rat striatum.

There is evidence that excitotoxicity and prolonged microglial activation are involved in neuronal death in neurodegenerative disorders. Activated microglia express various molecules, including the translocator protein 18 kDa (TSPO; formerly known as the peripheral benzodiazepine receptor) on the outer mitochondrial membrane. The TSPO is a novel target for neuroprotective treatments which aim to reduce microglial activation. The effect of PK 11195 and three other TSPO ligands on the level of microglial activation and neuronal survival was evaluated in a quinolinic acid (QUIN) rat model of excitotoxic neurodegeneration. All three ligands were neuroprotective at a level comparable to PK 11195. All of the ligands decreased microglial activation following the injection of QUIN but had no effect on astrogliosis. Interestingly, we also observed neuroprotective effects from the vehicle, dimethyl sulfoxide (DMSO).

Peru's national folic acid fortification program and its effect on neural tube defects in Lima.

OBJECTIVE: To evaluate the impact of Peru's national folic acid fortification program on folic acid content in wheat flour, and the effect on birth prevalence of neural tube defects (NTDs) in Lima, and to compare the program's legislative requirements with international standards. METHODS: Bread was sampled from six sites across Peru and tested for folic acid. Data were obtained from the largest obstetric hospital in Lima on the prevalence of births (live and still) with NTDs during both the pre-fortification period (2004-2005) and post-fortification years (2007-2008). RESULTS: Folic acid content in the sampled bread met national legislative requirements but was less than one-half of the level recommended for Peru by the World Health Organization (WHO) (2.6 mg/kg wheat flour). Birth prevalence of NTDs was 18.4/10 000 in the pre-fortification period and 20.0/10 000 during post-fortification years. Relative risk for NTDs after fortification was 1.02 (95% confidence interval 0.77-1.35, P = 0.90). CONCLUSIONS: Peruvian legislative requirements for folic acid fortification are below international (WHO) recommendations; birth prevalence of NTDs in Lima is higher than international benchmarks; and no decrease in NTDs following fortification of flour with folic acid (according to Peruvian national standards) was observed. As increasing the level of folic acid in flour remains the most sustainable way of preventing NTDs, it is recommended that Peru increase its folic acid fortification requirements to meet those recommended by WHO (2.6 mg/kg).

Oral pre-treatment with epigallocatechin gallate in 6-OHDA lesioned rats produces subtle symptomatic relief but not neuroprotection.

Much recent work is investigating the role of oxidative stress and inflammatory mechanisms in the aetiology of neurodegeneration in Parkinson's disease. The present study evaluated whether the green tea constituent epigallocatechin gallate (EGCG) which has both anti-oxidant and anti-inflammatory properties, exerts neuroprotection and symptomatic effects when administered orally as a pre-treatment prior to 6-hydroxydopamine (6-OHDA) lesions. Groups of rats were given either 1mg/kg, 2mg/kg EGCG or vehicle solution for 14 days. Sham or 6-OHDA surgery was performed on day 11 of the drug administration protocol. Behavioural analysis was conducted before drugs/vehicle solution, again during the treatment period and then repeated at fortnightly intervals for 2 months post-operatively. Whilst some subtle behavioural improvements in postural abnormalities and ability to cross a narrow beam were observed in lesioned rats after EGCG (vs. vehicle) there was no evidence of neuroprotection on post-mortem quantification of degree of nigral dopaminergic neuronal loss when comparing the lesioned groups given the various treatments.