Distribution of TDP-43 inclusions and neurons, and to a smaller extent of activated microglia, show a regional and hemispheric pattern consistent with disease phenotype and known patterns of atrophy in PPA with GRN mutations.

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 seen in cases 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 TDP-43 negative inclusions, we compared the clinical, pathologic, and genetic characteristics in 5 cases of FTLD-TDP and FTLD-MND with C9ORF72 mutations to 20 cases without mutations. We confirmed the apparent specificity of p62 positive, TDP-43 negative inclusions in cerebellum, hippocampus, cortex, and basal ganglia to FTLD with C9ORF72 mutations. p62 positive, TDP-43 negative inclusions in hippocampus correlated with hippocampal atrophy, but no additional correlations were uncovered. However, although ambiguity of TDP sub-typing has previously been reported in cases with C9ORF72 mutations, this is the first report to show that although most FTLD 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 TDP type B FTLD cases without mutations. These features 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 in FTLD cases with C9ORF72 mutations compared to FTLD-TDP type B cases without mutations, implying that the C9ORF72 mutation modifies the pathologic phenotype of FTLD-TDP type B.

Basal forebrain cholinergic neurons (BFCN) are selectively vulnerable in Alzheimer's disease (AD). We have shown that the majority of BFCN in the human brain contain the calcium binding protein calbindin-D28K (CB), a large proportion lose their CB in the course of normal aging, and the BFCN which degenerate in AD lack CB. Here we investigated the relationship between CB in the BFCN and the process of tangle formation in AD using antibodies to Tau epitopes that appear early, intermediate or late in the process of tangle formation. Very small percentages (0-3.7%) of CB-positive BFCN contained pre-tangles/tangles and very small percentages (0-5%) of the total BFCN pre-tangles/tangles were in CB-immunoreactive neurons. The number of CB-positive BFCN which contained Tau immunoreactivity was highest for the early epitope and lower for intermediate epitopes. A late appearing epitope was absent from CB-positive BFCN. Age-related loss of CB appears to coincide with tangle formation in the BFCN and is associated with the full range of Tau pathology, including late appearing epitopes.

BACKGROUND Lower grade gliomas (LGG) are heterogenous diseases by clinical, histological, and molecular criteria. We aimed to personalize the diagnosis and therapy of LGG patients by developing and validating robust cellular morphometric subtypes (CMS) and to uncover the molecular signatures underlying these subtypes. METHODS Cellular morphometric biomarkers (CMBs) were identified with artificial intelligence technique from TCGA-LGG cohort. Consensus clustering was used to define CMS. Survival analysis was performed to assess the clinical impact of CMBs and CMS. A nomogram was constructed to predict 3- and 5- year overall survival (OS) of LGG patients. Tumor mutational burden (TMB), and immune cell infiltration between subtypes were analyzed using the Mann-Whitney test. The double-blinded validation for important immunotherapy-related biomarkers were executed using immunohistochemistry (IHC). RESULTS We developed a machine learning pipeline to extract CMBs from whole slide images of tissue histology; identifying and externally validating robust CMS of LGGs in multi-center cohorts. The subtypes had independent predicted OS across all three independent cohorts. In the TCGA-LGG cohort, patients within the poor-prognosis subtype responded poorly to primary and follow-up therapies. LGGs within the poor-prognosis subtype were characterized by high mutational burden, high frequencies of copy number alterations, and high levels of tumor-infiltrating lymphocytes and immune checkpoint genes. Higher levels of PD-1/PD-L1/CTLA-4 were confirmed by immunohistochemical staining. In addition, the subtypes learned from LGG demonstrates translational impact on glioblastoma (GBM). CONCLUSIONS We developed and validated a framework (CMS-ML) for CMS discovery in LGG associated with specific molecular alterations, immune micro-environment, prognosis, and treatment response.