Manjari Mishra

FUS-immunoreactive inclusions are a common feature in sporadic and non-SOD1 familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disorder of motor neuron degeneration. Most cases of ALS are sporadic (SALS), but about 5 to 10% of ALS cases are familial (FALS). Recent studies have shown that mutations in FUS are causal in approximately 4 to 5% of FALS and some apparent SALS cases. The pathogenic mechanism of the mutant FUS‐mediated ALS and potential roles of FUS in non‐FUS ALS remain to be investigated.

Gene expression analysis of frontotemporal lobar degeneration of the motor neuron disease type with ubiquitinated inclusions

Neurodegenerative disorders share a process of aggregation of insoluble protein. Frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U) is characterized by the presence of ubiquitin and TDP-43 positive aggregates which are likely related to specific gene expression profiles. We carried out gene expression microarray analysis on post-mortem brain tissue from FTLD-U, FTLD-MND, and controls. Using total RNA from carefully dissected frontal cortical layer II, we obtained gene expression profiles showing that FTLD-U and controls differ in over 100 networks, including those involved in synapse formation, the ubiquitin-proteasome system, endosomal sorting, and apoptosis. We performed qRT-PCR validation for three genes, representative of three different networks. Dynein axonemal light intermediate chain 1 (DNALI1) (microtubule/cytoskeleton network associated) expression was 3-fold higher and myeloid differentiation primary response gene 88 (MYD88) (signal transduction network) was 3.3 times higher in FTLD-U than FTLD-MND and controls; annexin A2 (ANXA2) (endosomal sorting) expression was 11.3-fold higher in FTLD-U than FTLD-MND and 2.3-fold higher than controls. The identification of progranulin (PGRN) gene mutations and TDP-43 as the major protein component of the ubiquitinated inclusions, are two recent landmark discoveries in the field of FTLD-U. We found 1.5-fold increase in TDP-43 in both FTLD-MND and FTLD-U while progranulin showed no gene expression differences between controls and FTLD-MND. However, one of the FTLD-U cases tested by Affymetrix microarray showed “absence call” of this transcript, suggesting absent or decreased gene expression. Our findings point to specific gene-linked-pathways which may be influenced by neurodegenerative disease process and may be targeted for further exploration.

TDP-43 pathology in primary progressive aphasia and frontotemporal dementia with pathologic Alzheimer disease

The clinical syndrome of primary progressive aphasia (PPA) can be associated with a variety of neuropathologic diagnoses at autopsy. Thirty percent of cases have Alzheimer disease (AD) pathology, most often in the usual distribution, which defies principles of brain–behavior organization, in that aphasia is not symptomatic of limbic disease. The present study investigated whether concomitant TDP-43 pathology could resolve the lack of clinico-anatomic concordance. In this paper, 16 cases of clinical PPA and 10 cases of primarily non-aphasic frontotemporal dementia (FTD), all with AD pathology, were investigated to determine whether their atypical clinical phenotypes reflected the presence of additional TDP-43 pathology. A comparison group consisted of 27 cases of pathologic AD with the typical amnestic clinical phenotype of probable AD. Concomitant TDP-43 pathology was discovered in only three of the FTD and PPA but in more than half of the typical amnestic clinical phenotypes. Hippocampal sclerosis (HS) was closely associated with TDP-43 pathology when all groups were combined for analysis. Therefore, the clinical phenotypes of PPA and FTD in cases with pathologic AD are only rarely associated with TDP-43 proteinopathy. Furthermore, medial temporal TDP-43 pathology is more tightly linked to HS than to clinical phenotype. These findings challenge the current notions about clinicopathologic correlation, especially about the role of multiple pathologies.

Differential Involvement of Optineurin in Amyotrophic Lateral Sclerosis With or Without SOD1 Mutations

BACKGROUND Mutations in optineurin have recently been linked to amyotrophic lateral sclerosis (ALS). OBJECTIVE To determine whether optineurin-positive skeinlike inclusions are a common pathologic feature in ALS, including SOD1 -linked ALS. DESIGN Clinical case series. SETTING Academic referral center. SUBJECTS We analyzed spinal cord sections from 46 clinically and pathologically diagnosed ALS cases and ALS transgenic mouse models overexpressing ALS-linked SOD1 mutations G93A or L126Z. RESULTS We observed optineurin-immunoreactive skeinlike inclusions in all the sporadic ALS and familial ALS cases without SOD1 mutation, but not in cases with SOD1 mutations or in transgenic mice overexpressing the ALS-linked SOD1 mutations G93A or L126Z. CONCLUSION The data from this study provide evidence that optineurin is involved in the pathogenesis of sporadic ALS and non- SOD1 familial ALS, thus supporting the hypothesis that these forms of ALS share a pathway that is distinct from that of SOD1-linked ALS.

Plasma phosphorylated-TDP-43 protein levels correlate with brain pathology in frontotemporal lobar degeneration

In the present study, we have correlated plasma TDP-43 levels, as measured by ELISA, with the presence of TDP-43 pathological changes in the brains of 28 patients with frontotemporal lobar degeneration (FTLD) (14 with FTLD-TDP and 14 with FTLD-tau) and 24 patients with pathologically confirmed AD (8 with, and 16 without, TDP-43 pathological changes). Western blotting revealed full-length TDP-43, including a phosphorylated form, and a phosphorylated C-terminal fragment, in all samples examined. Both ELISA and immunohistochemistry were performed using phospho-dependent and phospho-independent TDP-43 antibodies for detection of phosphorylated and total TDP-43, respectively. Over all 52 cases, plasma levels of TDP-43, and scores of brain TDP-43 pathology, determined using TDP-43 phospho-dependent antibody correlated with the equivalent measure determined using the TDP phospho-independent antibody. In FTLD, but not AD, TDP-43 plasma levels correlated significantly with the pathology score when using the TDP-43 phospho-dependent antibody, but a similar correlation was not seen in either FTLD or AD using the TDP-43 phospho-independent antibody. With the TDP-43 phospho-independent antibody, there were no significant differences in median plasma TDP-43 levels between FTLD, or AD, patients with or without TDP-43 pathology. Using TDP-43 phospho-dependent antibody, median plasma TDP-43 levels were greater in patients with, than in those without, TDP-43 pathology for FTLD patients, though not significantly so, but not for AD patients. Present assays for TDP-43 do not differentiate between FTLD, or AD, patients with or without TDP-43 pathological changes in their brains. However, the levels of phosphorylated TDP-43 in plasma do correlate with the extent of TDP-43 brain pathology in FTLD, and therefore might be a useful surrogate marker for tracking changes in TDP-43 brain pathology during the course of this disease.

Clinicopathologic correlation in PGRN mutations

Background: Frontotemporal dementia (FTD) has been linked to the microtubule associated protein tau (MAPT) gene region of chromosome 17. However, many chromosome-17 linked FTLDs do not have MAPT mutations or tau protein deposits, but have ubiquitin positive, tau and alpha-synuclein negative inclusions. Mutations in the progranulin (PGRN) gene, located 1.7 Mb from MAPT at 17q21.31, were recently discovered in some of these individuals. The pathologic phenotype in all cases has thus far included ubiquitinated neuronal intranuclear inclusions (NIIs) and neuronal cytoplasmic inclusions (NCIs). Methods: PGRN mutation analysis was performed in 12 individuals. Informed consent was obtained from next of kin under an IRB-approved protocol. We compared clinical and pathologic findings in those cases with and without PGRN mutations. Results: PGRN mutations were found in four patients, two with clinical FTD and a positive family history, and two with clinical primary progressive aphasia (PPA), one with and one without a family history. All four cases with, and five of eight cases without, PGRN mutations had ubiquitinated NCIs and NIIs. Brains of individuals with PGRN mutations are associated with more frequent frontal NCIs and dystrophic neurites, less frequent dentate gyrus NCIs, and more frequent striatal NIIs than FTLD-U cases without PGRN mutations. Conclusion: PGRN mutations at 17q21 may occur in apparently sporadic frontotemporal lobar dementia with ubiquitinated inclusions cases and in cases presenting with either primary progressive aphasia or the behavioral variant of frontotemporal dementia. Some cases without PGRN mutations also have ubiquitinated neuronal intranuclear inclusions. Clinicopathologic differences are observed among individuals with and without PGRN mutations.

ApoE E4 is a susceptibility factor in amnestic but not aphasic dementias.

The goal of this study was to determine if the apolipoprotein &egr; gene, which is a well-established susceptibility factor for Alzheimer disease (AD) pathology in typical amnestic dementias, may also represent a risk factor in the language-based dementia, primary progressive aphasia (PPA). Apolipoprotein E genotyping was obtained from 149 patients with a clinical diagnosis of PPA, 330 cognitively healthy individuals (NC), and 179 patients with a clinical diagnosis of probable Alzheimers disease (PrAD). Allele frequencies were compared among the groups. Analyses were also completed by sex and in 2 subsets of PPA patients: 1 in which the patients were classified by subtype (logopenic, agrammatic, and semantic) and another in which pathologic data were available. The allele frequencies for the PPA group (&egr;2:5%, &egr;3:79.5%, and &egr;4:15.4%) showed a distribution similar to the NC group, but significantly different from the PrAD group. The presence of an &egr;4 allele did not influence the age of symptom onset or aid in the prediction of AD pathology in PPA. These data show that &egr;4 polymorphism, which is a well-known risk factor for AD pathology in typical amnestic dementias, has no similar relationship to the clinical syndrome of PPA or its association with AD pathology.

Frontotemporal lobar degeneration with TDP‐43 proteinopathy and chromosome 9p repeat expansion in C9ORF72: clinicopathologic correlation

Mutations in C9ORF72 resulting in expanded hexanucleotide repeats were recently reported to be the underlying genetic abnormality in chromosome 9p‐linked frontotemporal lobar degeneration with TAR DNA‐binding protein of 43 kD (TDP‐43) proteinopathy (FTLD‐TDP), amyotrophic lateral sclerosis (ALS), and frontotemporal lobar degeneration with motor neuron disease (FTLD‐MND). Several subsequent publications described the neuropathology as being similar to that of FTLD‐TDP and ALS without C9ORF72 mutations, except that cases with mutations have p62 and ubiquitin positive, TDP‐43 negative inclusions in cerebellum, hippocampus, neocortex, and basal ganglia. The identity of this protein is as yet unknown, and its significance is unclear. With the goal of potentially uncovering the significance of these inclusions, we compared the clinical, pathologic and genetic characteristics in cases with C9ORF72 mutations to those without. We confirmed the apparent specificity of p62 positive, TDP‐43 negative inclusions to cases with C9ORF72 mutations. In hippocampus, these inclusions correlated with hippocampal atrophy. No additional correlations were uncovered. However, this is the first report to show that although most cases with C9ORF72 mutations were TDP type B, some of the pathologic characteristics in these cases were more similar to TDP types A and C than to type B cases. These include greater cortical and hippocampal atrophy, greater ventricular dilatation, more neuronal loss and gliosis in temporal lobe and striatum, and TDP‐43 positive fine neuritic profiles in the hippocampus, implying that the C9ORF72 mutation modifies the pathologic phenotype of FTLD‐TDP type B.

Nuclear Carrier and RNA Binding Proteins in Frontotemporal Lobar Degeneration associated with Fused in Sarcoma (FUS) pathological changes

Y. S. Davidson, A. C. Robinson, Q. Hu, M. Mishra, A. Baborie, E. Jaros, R. H. Perry, N. J. Cairns, A. Richardson, A. Gerhard, D. Neary, J. S. Snowden, E. H. Bigio and D. M. A. Mann (2013) Neuropathology and Applied Neurobiology39, 157–165

Asymmetric TDP-43 distribution in primary progressive aphasia with progranulin mutation

Objective: Primary progressive aphasia (PPA) results from an asymmetric degeneration of the language dominant (usually left) hemisphere and can be associated with the pathology of Alzheimer disease (AD) or frontotemporal lobar degeneration (FTLD). This study aimed to investigate whether the anatomic distribution of TDP-43 inclusions displayed a corresponding leftward asymmetry in a patient with PPA with a mutation in the progranulin gene and FTLD pathology. Methods: Brain tissue from a 65-year-old patient with PPA and progranulin mutation was analyzed using immunohistochemical methods for TDP-43. Analysis was performed in the superior temporal gyrus, inferior temporal gyrus, inferior parietal lobule, orbitofrontal cortex, entorhinal cortex, and dentate gyrus. Neuronal intranuclear inclusions, neuronal cytoplasmic inclusions, and dystrophic neurites were quantified using modified stereologic analysis. Analysis of variance was used to determine significant effects. Results: All 3 types of inclusions predominated on the left side of analyzed cortical regions. They were also more frequent in language areas than in memory-related areas. Conclusion: These results demonstrate a phenotypically concordant distribution of abnormal TDP-43 inclusions in primary progressive aphasia (PPA). This contrasts with PPA cases with Alzheimer pathology where no consistent leftward asymmetry of neurofibrillary degeneration or amyloid deposition has been demonstrated despite the leftward asymmetry of the atrophy, and where neurofibrillary tangles show a greater density in memory than language areas despite the predominantly aphasic phenotype. This case suggests that the TDP-43 inclusions in PPA–frontotemporal lobar degeneration are more tightly linked to neuronal death and dysfunction than neurofibrillary and amyloid deposits in PPA–Alzheimer disease.