Increase in wasteosomes (corpora amylacea) in frontotemporal lobar degeneration with specific detection of tau, TDP-43 and FUS pathology.

Wasteosomes (or corpora amylacea) are polyglucosan bodies that appear in the human brain with aging and in some neurodegenerative diseases, and have been suggested to have a potential role in a nervous system cleaning mechanism. Despite previous studies in several neurodegenerative disorders, their status in frontotemporal lobar degeneration (FTLD) remains unexplored. Our study aims to characterize wasteosomes in the three primary FTLD proteinopathies, assessing frequency, distribution, protein detection, and association with aging or disease duration. Wasteosome scores were obtained in various brain regions from 124 post-mortem diagnosed sporadic FTLD patients, including 75 participants with tau (FTLD-tau), 42 with TAR DNA-binding protein 43 (FTLD-TDP), and 7 with Fused in Sarcoma (FTLD-FUS) proteinopathies, along with 29 control subjects. The wasteosome amount in each brain region for the different FLTD patients was assessed with a permutation test with age at death and sex as covariables, and multiple regressions explored associations with age at death and disease duration. Double immunofluorescence studies examined altered proteins linked to FTLD in wasteosomes. FTLD patients showed a higher accumulation of wasteosomes than control subjects, especially those with FTLD-FUS. Unlike FTLD-TDP and control subjects, wasteosome accumulation did not increase with age in FTLD-tau and FTLD-FUS. Cases with shorter disease duration in FTLD-tau and FTLD-FUS seemed to exhibit higher wasteosome quantities, whereas FTLD-TDP appeared to show an increase with disease progression. Immunofluorescence studies revealed the presence of tau and phosphorylated-TDP-43 in the periphery of isolated wasteosomes in some patients with FTLD-tau and FTLD-TDP, respectively. Central inclusions of FUS were observed in a higher number of wasteosomes in FTLD-FUS patients. These findings suggest a role of wasteosomes in FTLD, especially in the more aggressive forms of FLTD-FUS. Detecting these proteins, particularly FUS, in wasteosomes from cerebrospinal fluid could be a potential biomarker for FTLD.

Genetic variation in APOE, GRN, and TP53 are phenotype modifiers in frontotemporal dementia.

Frontotemporal dementia (FTD) is a clinical, genetic, and pathologic heterogeneous group of neurodegenerative diseases. In this study, we investigated the role of APOƐ4, rs5848 in GRN, and rs1042522 in TP53 gene as disease risk factors and/or phenotype modifiers in 440 FTD patients, including 175 C9orf72 expansion carriers. We found that the C9orf72 expansion carriers showing an earlier age at onset (p < 0.001). Among the clinical groups, the FTD-MND (motoneuron disease) showed the lowest survival (hazard ratio [HR] = 4.12), and the progressive nonfluent aphasia group showed the highest onset age (p = 0.03). In our cohort, the rs1042522 in TP53 was associated with disease onset (p = 0.02) and survival (HR = 1.73) and rs5848 GRN with a significantly shorter survival in CC homozygous patients (HR = 1.98). The frequency of APOƐ4 carriers was significantly increased in the C9orf72 noncarriers (p = 0.022). Although validation of our findings is necessary, our results suggest that TP53, GRN, and APOE genes may act as phenotype modifiers in FTD and should be considered in future clinical trials.

APP-derived peptides reflect neurodegeneration in frontotemporal dementia.

OBJECTIVE: We aimed to investigate the relationship between cerebrospinal fluid levels (CSF) of amyloid precursor protein (APP)-derived peptides related to the amyloidogenic pathway, cortical thickness, neuropsychological performance, and cortical gene expression profiles in frontotemporal lobar degeneration (FTLD)-related syndromes, Alzheimer's disease (AD), and healthy controls. METHODS: We included 214 participants with CSF available recruited at two centers: 93 with FTLD-related syndromes, 57 patients with AD, and 64 healthy controls. CSF levels of amyloid ß (Aß)1-42, Aß1-40, Aß1-38, and soluble ß fragment of APP (sAPPß) were centrally analyzed. We compared CSF levels of APP-derived peptides between groups and, we studied the correlation between CSF biomarkers, cortical thickness, and domain-specific cognitive composites in each group. Then, we explored the relationship between cortical thickness, CSF levels of APP-derived peptides, and regional gene expression profile using a brain-wide regional gene expression data in combination with gene set enrichment analysis. RESULTS: The CSF levels of Aß1-40, Aß1-38, and sAPPß were lower in the FTLD-related syndromes group than in the AD and healthy controls group. CSF levels of all APP-derived peptides showed a positive correlation with cortical thickness and the executive cognitive composite in the FTLD-related syndromes group but not in the healthy control or AD groups. In the cortical regions where we observed a significant association between cortical thickness and CSF levels of APP-derived peptides, we found a reduced expression of genes related to synaptic function. INTERPRETATION: APP-derived peptides in CSF may reflect FTLD-related neurodegeneration. This observation has important implications as Aß1-42 levels are considered an indirect biomarker of cerebral amyloidosis.

Altered Blood Gene Expression of Tumor-Related Genes (PRKCB, BECN1, and CDKN2A) in Alzheimer's Disease.

Alzheimer's disease (AD) is the most common of the neurodegenerative diseases. Recent diagnostic criteria have defined a preclinical disease phase during which neuropathological substrates are thought to be present in the brain. There is an urgent need to find measurable alterations in this phase as well as a good peripheral biomarker in the blood. We selected a cohort of 100 subjects (controls = 47; preclinical AD = 11; patients with AD = 42) and analyzed whole blood expression of 20 genes by quantitative polymerase chain reaction. The selected genes belonged to calcium signaling, senescence and autophagy, and mitochondria/oxidative stress pathways. Additionally, two genes associated with an increased risk of developing AD (clusterin (CLU) and bridging integrator 1 (BIN1)) were also analyzed. We detected significantly different gene expressions of BECN1 and PRKCB between the control and the AD groups and of CDKN2A between the control and the preclinical AD groups. Notably, these three genes are also considered tumor suppressor (CDKN2A and BECN1) or tumor promoter (PRKCB) genes. Gene-gene expression Pearson correlations were computed separately for controls and patients with AD. The significant correlations (p < 0.001) were represented in a network analysis with Cytoscape tool, which suggested an uncoupling of mitochondria-related genes in AD group. Whole blood is emerging as a valuable tissue in the study of the physiopathology of AD.

Phenotypic variability within the inclusion body spectrum of basophilic inclusion body disease and neuronal intermediate filament inclusion disease in frontotemporal lobar degenerations with FUS-positive inclusions.

Basophilic inclusion body disease and neuronal intermediate filament inclusion disease (NIFID) are rare diseases included among frontotemporal lobar degenerations with FUS-positive inclusions (FTLD-FUS). We report clinical and pathologic features of 2 new patients and reevaluate neuropathologic characteristics of 2 previously described cases, including an early-onset case of basophilic inclusion body disease (aged 38 years) with a 5-year disease course and abundant FUS-positive inclusion bodies and 3 NIFID cases. One NIFID case (aged 37 years) presented with early-onset psychiatric disturbances and rapidly progressive cognitive decline. Two NIFID cases had later onset (aged 64 years and 70 years) and complex neurologic deficits. Postmortem neuropathologic studies in late-onset NIFID cases disclosed α-internexin-positive "hyaline conglomerate"-type inclusions that were positive with 1 commercial anti-FUS antibody directed to residues 200 and 250, but these were negative to amino acids 90 and 220 of human FUS. Early-onset NIFID had similar inclusions that were positive with both commercial anti-FUS antibodies. Genetic testing performed on all cases revealed no FUS gene mutations. These findings indicate that phenotypic variability in NIFID, including clinical manifestations and particular neuropathologic findings, may be related to the age at onset and individual differences in the evolution of lesions.

Cellular crosstalk between TNF-α, NADPH oxidase, PKCß2, and C2GNT in human leukocytes.

Increasing evidence suggests that chronic, sub-clinical inflammation plays an important role in the pathogenesis of diabetic retinopathy. We have established the potential role of the inflammatory enzyme, core 2 ß-1, 6-N-acetylglucosaminyltransferase (C2GNT) in diabetic retinopathy. The present study was designed to explore the NADPH oxidase signaling pathway in the tumor necrosis factor-alpha (TNF-α)-induced activity of C2GNT in leukocytes. Human leukocytes (U937 cells) and an Epstein-Barr-transformed lymphoblastoid cell line deficient in p47phox (F10007 cells) were used for the study. Cells were exposed to TNF-α for 24h in the presence and absence of 1) NADPH oxidase inhibitors (apocynin and scrambled and unscrambled gp91ds-tat), 2) LY379196 (specific protein kinase C ß1/2 (PKCß1/2) inhibitor), and 3) the antioxidant tiron. Subsequent C2GNT and NADPH activity was measured and the adhesion of U937 and F10007 cells to endothelial cells was assessed. TNF-α-induced C2GNT activity (1813±326 pmol/h/mg protein) (mean±SEM) in human leukocytes was significantly reversed with apocynin (153±82 pmol/h/mg protein), unscrambled gp91ds-tat (244±122 pmol/h/mg protein) and tiron (756±87 pmol/h/mg protein). We further supported this C2GNT-NADPH oxidase link using p47phox-deficient leukocytes. The deficiency in p47phox prevented TNF-α-induced NADPH oxidase and C2GNT activity and adherence to endothelial cells. The response to TNF-α was restored by transfection with an expression plasmid containing a p47phox cDNA inserted in the sense direction. Our results demonstrate for the first time a novel signaling crosstalk between TNF-α, NADPH oxidase, PKCß1/2 and C2GNT in leukocytes.