Dickson, Dennis W.

The most recent late-onset Alzheimer's disease (LOAD) genome-wide association study revealed genome-wide significant association of two new loci: rs744373 near BIN1 (p = 1.6 × 10 −11 ) and rs597668 near EXOC3L2/BLOC1S3/MARK4 (p = 6.5 × 10 −9 ). We have genotyped these variants in a large (3,287 LOAD, 4,396 controls), independent dataset comprising eleven case-control series from the USA and Europe. We performed meta-analyses of the association of these variants with LOAD and also tested for association using logistic regression adjusted by age-at-diagnosis, gender, and APOE ε4 status. Meta-analysis results showed no evidence of series heterogeneity and logistic regression analysis successfully replicated the association of BIN1 (rs744373) with LOAD with an odds ratio (OR = 1.17, p = 1.1 × 10 −4 ) comparable to that previously reported (OR = 1.15). The variant near EXOC3L2 (rs597668) showed only suggestive association with LOAD (p = 0.09) after correcting for the presence of the APOE ε4 allele. Addition of our follow-up data to the results previously reported increased the strength of evidence for association with BIN1 (11,825 LOAD, 32,570 controls, rs744373 Fisher combined p = 3.8 × 10 −20 ). We also tested for epistatic interaction between these variants and APOE ε4 as well as with the previously replicated LOAD GWAS genes (CLU: rs11136000, CR1: rs3818361, and PICALM: rs3851179). No significant interactions between these genes were detected. In summary, we provide additional evidence for the variant near BIN1 (rs744373) as a LOAD risk modifier, but our results indicate that the effect of EXOC3L2 independent of APOE ε4 should be studied further.

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AimsThis study aimed to assess clinicopathologic features of transactive response DNA‐binding protein of 43 kDa (TDP‐43) pathology and its risk factors in multiple system atrophy (MSA).MethodsParaffin‐embedded sections of the amygdala and basal forebrain from 186 autopsy‐confirmed MSA cases were screened with immunohistochemistry for phospho‐TDP‐43. In cases having TDP‐43 pathology, additional brain regions were assessed. Immunohistochemical and immunofluorescence double‐staining and immunogold electron microscopy (IEM) were performed to evaluate colocalization of TDP‐43 and α‐synuclein. Genetic risk factors for TDP‐43 pathology were also analysed.ResultsImmunohistochemistry showed various morphologies of TDP‐43 pathology in 13 cases (7%), such as subpial astrocytic inclusions, neuronal inclusions, dystrophic neurites, perivascular inclusions and glial cytoplasmic inclusions (GCIs). Multivariable logistic regression models revealed that only advanced age, but not concurrent Alzheimer's disease, argyrophilic grain disease or hippocampal sclerosis, was an independent risk factor for TDP‐43 pathology in MSA (OR: 1.11, 95% CI: 1.04–1.19, P = 0.002). TDP‐43 pathology was restricted to the amygdala in eight cases and extended to the hippocampus in two cases. The remaining three cases had widespread TDP‐43 pathology. Immunohistochemical and immunofluorescence double‐staining and IEM revealed colocalization of α‐synuclein and TDP‐43 in GCIs with granule‐coated filaments. Pilot genetic studies failed to show associations between risk variants of TMEM106B or GRN and TDP‐43 pathology.ConclusionsTDP‐43 pathology is rare in MSA and occurs mainly in the medial temporal lobe. Advanced age is a risk factor for TDP‐43 pathology in MSA. Colocalization of TDP‐43 and α‐synuclein in GCIs suggests possible direct interaction between the two molecules.

Background: Mutations in the leucine rich repeat kinase 2 ( LRRK2) gene are among the most common genetic causes of Lewy body Parkinson’s disease (PD). However, LRRK2 mutations can also lead to a variety of pathological phenotypes other than typical PD, including relatively pure nigrostriatal cell loss without alpha-synuclein-positive Lewy bodies or Lewy neurites, progressive supranuclear palsy (PSP), and multiple system atrophy (MSA). The mechanisms behind this remarkable pleomorphic pathology are currently unclear. Objective: To genetically and pathologically characterize a case with a LRRK2, p.Ile1371Val rare variant and pathologically proven MSA. Methods: From the brain donation program at the Parkinson’s Institute and Clinical Center, we selected 26 brains with family history and a with clinicopathological diagnosis of PD ( n = 20), MSA ( n = 4), or PSP ( n = 2). We performed neuropathological evaluation, including alpha-synuclein and tau immunohistochemistry and sequenced 188 genes that have been reported as causative for or associated with neurodegenerative diseases. Results: We identified a known LRRK2, p.Ile1371Val genetic variant in a case with clinically diagnosed and pathologically proven MSA. Neuropathology revealed that the olivopontocerebellar system was more affected than the striatonigral system. Conclusions: Our data suggest that genetic variants in the LRRK2 gene can present clinically and neuropathologically as MSA. One other LRRK2 genetic variant ( LRRK2, p.Ile2020Thr) has been reported with a neuropathological diagnosis of MSA. Interestingly, the LRRK2 variant ( LRRK2, p.Ile1371Val) identified here has been reported previously in a postmortem case with Lewy body PD. Future studies are critical to discover the mechanisms leading to different neurodegenerative trajectories both in neuronal and glial cell populations.

ABSTRACTBackground: Dysregulation of the specialized lipid metabolism involved in myelin synthesis and maintenance by oligodendrocytes has been associated with the unique neuropathology of MSA. We hypothesized that apolipoprotein E, which is associated with neurodegeneration, may also play a role in the pathogenesis of MSA.Objective: This study evaluated genetic associations of Apolipoprotein E alleles with risk of MSA and α‐synuclein pathology, and also examined whether apolipoprotein E isoforms differentially affect α‐synuclein uptake in a oligodendrocyte cell.Methods: One hundred sixty‐eight pathologically confirmed MSA patients, 89 clinically diagnosed MSA patients, and 1,277 control subjects were genotyped for Apolipoprotein E. Human oligodendrocyte cell lines were incubated with α‐synuclein and recombinant human apolipoprotein E, with internalized α‐synuclein imaged by confocal microscopy and cells analyzed by flow cytometry.Results: No significant association with risk of MSA or was observed for either Apolipoprotein E ɛ2 or ɛ4. α‐Synuclein burden was also not associated with Apolipoprotein E alleles in the pathologically confirmed patients. Interestingly, in our cell assays, apolipoprotein E ɛ4 significantly reduced α‐synuclein uptake in the oligodendrocytic cell line.Conclusions: Despite differential effects of apolipoprotein E isoforms on α‐synuclein uptake in a human oligodendrocytic cell, we did not observe a significant association at the Apolipoprotein E locus with risk of MSA or α‐synuclein pathology. © 2018 International Parkinson and Movement Disorder Society

AbstractThe relationship between clinicopathologic diagnosis and 123I‐FP‐CIT SPECT in 18 patients with dementia (12 with Lewy body disease) from one center in the United States was assessed. The sensitivity and specificity of abnormal 123I‐FP‐CIT SPECT with reduced striatal uptake on visual inspection for predicting Lewy body disease were 91.7% and 83.3%, respectively. The mean calculated putamen to occipital ratio (mPOR) based on regions of interest was significantly reduced in Lewy body disease compared to non‐Lewy body disease cases (P = 0.002). In this study, abnormal 123I‐FP‐CIT SPECT was strongly associated with underlying Lewy body disease pathology, supporting the utility of 123I‐FP‐CIT SPECT in the clinical diagnosis of dementia with Lewy bodies.

AimsThe human epidermal growth factor receptor family consists of four members that belong to the ErbB lineage of proteins (ErbB1‐4). Neuregulin‐1 (NRG1)/ErbB signalling regulates brain development and function. Abnormalities in this signalling have been implicated in the aetiology or development of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. So, we aimed at investigating whether the expression of NRG1 or ErbB proteins are altered in progressive supranuclear palsy (PSP).MethodsThe brains of 10 PSP and six control patients were investigated by immunohistochemical analysis.ResultsWhereas C‐terminal ErbB4 immunoreacitivity was partially but distinctly present in the cytoplasm and/or in the nucleus of neurons in control patients, it was rarely observed in the neuronal nuclei in PSP patients. In contrast, neurofibrillary tangles, coiled bodies and threads were robustly immunoreactive for C‐terminal ErbB4 in PSP. Double immunofluorescence for C‐terminal ErbB4 and phospho‐tau revealed co‐localization of these proteins within neuronal and glial inclusions. To the contrary, there was no difference in the subcellular localization of NRG1, ErbB1, ErbB2, and N‐terminal ErbB4 between control and PSP patients. These proteins were localized in the cytoplasm of neurons.ConclusionsOur present results suggest that NRG1/ErbB4 signalling could be an important event in the pathogenesis of PSP.

Mutant Tau (MAPT) can lead to frontotemporal lobar degeneration (FTLD). Previous studies associated MAPT mutations and altered function with aneuploidy and chromosome instability in human lymphocytes and in Drosophila development. Here we examine whether FTLD-causing mutations in human MAPT induce aneuploidy and apoptosis in the mammalian brain. First, aneuploidy was found in brain cells from MAPT mutant transgenic mice expressing FTLD mutant human MAPT. Then brain neurons from mice homozygous or heterozygous for the Tau (Mapt) null allele were found to exhibit increasing levels of aneuploidy with decreasing Tau gene dosage. To determine whether aneuploidy leads to neurodegeneration in FTLD, we measured aneuploidy and apoptosis in brain cells from patients with MAPT mutations and identified both increased aneuploidy and apoptosis in the same brain neurons and glia. To determine whether there is a direct relationship between MAPT-induced aneuploidy and apoptosis, we expressed FTLD-causing mutant forms of MAPT in karyotypically normal human cells and found that they cause aneuploidy and mitotic spindle defects that then result in apoptosis. Collectively, our findings reveal a neurodegenerative pathway in FTLD-MAPT in which neurons and glia exhibit mitotic spindle abnormalities, chromosome mis-segregation, and aneuploidy, which then lead to apoptosis.