Frequency of LATE neuropathologic change across the spectrum of Alzheimer's disease neuropathology: combined data from 13 community-based or population-based autopsy cohorts.

An international consensus report in 2019 recommended a classification system for limbic-predominant age-related TDP-43 encephalopathy neuropathologic changes (LATE-NC). The suggested neuropathologic staging system and nomenclature have proven useful for autopsy practice and dementia research. However, some issues remain unresolved, such as cases with unusual features that do not fit with current diagnostic categories. The goal of this report is to update the neuropathologic criteria for the diagnosis and staging of LATE-NC, based primarily on published data. We provide practical suggestions about how to integrate available genetic information and comorbid pathologies [e.g., Alzheimer’s disease neuropathologic changes (ADNC) and Lewy body disease]. We also describe recent research findings that have enabled more precise guidance on how to differentiate LATE-NC from other subtypes of TDP-43 pathology [e.g., frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS)], and how to render diagnoses in unusual situations in which TDP-43 pathology does not follow the staging scheme proposed in 2019. Specific recommendations are also made on when not to apply this diagnostic term based on current knowledge. Neuroanatomical regions of interest in LATE-NC are described in detail and the implications for TDP-43 immunohistochemical results are specified more precisely. We also highlight questions that remain unresolved and areas needing additional study. In summary, the current work lays out a number of recommendations to improve the precision of LATE-NC staging based on published reports and diagnostic experience.

NHERF1/EBP50, an adaptor protein required for epithelial morphogenesis, has been implicated in the progression of various human malignancies. NHERF1-deficient mice have intestinal brush border structural defects and we report here that they also have disorganized ependymal cilia with development of non-obstructive hydrocephalus. Examination of mouse and human brain tissues revealed highest NHERF1 expression at the apical plasma membrane of ependymal cells. In ependymal tumors, NHERF1 expression was retained in polarized membrane structures, such as microlumens, rosettes and canals, where it co-localized with some of its ligands, such as moesin and PTEN. Analysis of a comprehensive panel of 113 tumors showed robust NHERF1 labeling of microlumens in 100% of ependymomas, subependymomas, and pediatric anaplastic ependymomas, and in 67% of adult anaplastic ependymomas. NHERF1 staining was present in 35% of ependymoma cases that lacked reactivity for EMA, the routine immunohistochemical marker used for ependymoma diagnosis. NHERF1 labeling of microlumens was either absent or rarely seen in other types of brain tumors analyzed, denoting NHERF1 as a reliable diagnostic marker of ependymal tumors. Anaplastic foci and a subset of adult anaplastic ependymomas showed complete absence of NHERF1-labeled polarity structures, consistent with a loss of differentiation in these aggressive tumors. These data highlight a role for NHERF1 in ependymal morphogenesis with direct application to the diagnosis of ependymal tumors.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-015-0197-z) contains supplementary material, which is available to authorized users.

Tau aggregates are present in multiple neurodegenerative diseases known as “tauopathies,” including Alzheimer’s disease, Pick’s disease, progressive supranuclear palsy, and corticobasal degeneration. Such misfolded tau aggregates are therefore potential sources for selective detection and biomarker discovery. Six human tau isoforms present in brain tissues and both 3R and 4R isoforms have been observed in the neuronal inclusions. To develop selective markers for AD and related rare tauopathies, we first used an engineered tau protein fragment 4RCF as the substrate for ultrasensitive real-time quaking-induced conversion analyses (RT-QuIC). We showed that misfolded tau from diseased AD and other tauopathy brains were able to seed recombinant 4RCF substrate. We further expanded to use six individual recombinant tau isoforms as substrates to amplify misfolded tau seeds from AD brains. We demonstrated, for the first time to our knowledge, that misfolded tau from the postmortem AD brain tissues was able to specifically seed all six full-length human tau isoforms. Our results demonstrated that RT-QuIC analysis can discriminate AD and other tauopathies from non-AD normal controls. We further uncovered that 3R-tau isoforms displayed significantly faster aggregation kinetics than their 4R-tau counterparts under conditions of both no seeding and seeding with AD brain homogenates. In summary, our work offers potential new avenues of misfolded tau detection as potential biomarkers for diagnosis of AD and related tauopathies and provides new insights into isoform-specific human tau aggregation.