Alzheimer's disease (AD) is characterized by the deposition of senile plaques (SPs) and neurofibrillary tangles (NFTs) in vulnerable brain regions. SPs are composed of aggregated beta-amyloid (Abeta) 40/42(43) peptides. Evidence implicates a central role for Abeta in the pathophysiology of AD. Mutations in betaAPP and presenilin 1 (PS1) lead to elevated secretion of Abeta, especially the more amyloidogenic Abeta42. Immunohistochemical studies have also emphasized the importance of Abeta42 in initiating plaque pathology. Cell biological studies have demonstrated that Abeta is generated intracellularly. Recently, endogenous Abeta42 staining was demonstrated within cultured neurons by confocal immunofluorescence microscopy and within neurons of PS1 mutant transgenic mice. A central question about the role of Abeta in disease concerns whether extracellular Abeta deposition or intracellular Abeta accumulation initiates the disease process. Here we report that human neurons in AD-vulnerable brain regions specifically accumulate gamma-cleaved Abeta42 and suggest that this intraneuronal Abeta42 immunoreactivity appears to precede both NFT and Abeta plaque deposition. This study suggests that intracellular Abeta42 accumulation is an early event in neuronal dysfunction and that preventing intraneuronal Abeta42 aggregation may be an important therapeutic direction for the treatment of AD.

The excessive generation and accumulation of 40- and 42-aa β-amyloid peptides (Aβ ₄₀ /Aβ ₄₂ ) in selectively vulnerable brain regions is a major neuropathological feature of Alzheimer’s disease. Aβ, derived by proteolytic cleavage from the β-amyloid precursor protein (βAPP), is normally secreted. However, recent evidence suggests that significant levels of Aβ also may remain inside cells. Here, we have investigated the subcellular compartments within which distinct amyloid species are generated and the compartments from which they are secreted. Three experimental approaches were used: ( i ) immunofluorescence performed in intact cortical neurons; ( ii ) sucrose gradient fractionation performed with mouse neuroblastoma cells stably expressing wild-type βAPP ₆₉₅ (N2a ₆₉₅ ); and ( iii ) cell-free reconstitution of Aβ generation and trafficking from N2a ₆₉₅ cells. These studies demonstrate that: ( i ) Aβ ₄₀ (Aβ _1–40 plus Aβ _x-40 , where x is an NH ₂ -terminal truncation) is generated exclusively within the trans-Golgi Network (TGN) and packaged into post-TGN secretory vesicles; ( ii ) Aβ _x-42 is made and retained within the endoplasmic reticulum in an insoluble state; ( iii ) Aβ ₄₂ (Aβ _1–42 plus Aβ _x-42 ) is made in the TGN and packaged into secretory vesicles; and ( iv ) the amyloid peptides formed in the TGN consist of two pools (a soluble population extractable with detergents and a detergent-insoluble form). The identification of the organelles in which distinct forms of Aβ are generated and from which they are secreted should facilitate the identification of the proteolytic enzymes responsible for their formation.

Alzheimer's disease (AD) is characterized by the age-related deposition of β-amyloid (Aβ) 40/42 peptide aggregates in vulnerable brain regions. Multiple levels of evidence implicate a central role for Aβ in the pathophysiology of AD. Aβ peptides are generated by the regulated cleavage of an ≈700-aa Aβ precursor protein (βAPP). Full-length βAPP can undergo proteolytic cleavage either within the Aβ domain to generate secreted sβAPPα or at the N- and C-terminal domain(s) of Aβ to generate amyloidogenic Aβ peptides. Several epidemiological studies have reported that estrogen replacement therapy protects against the development of AD in postmenopausal women. We previously reported that treating cultured neurons with 17β-estradiol reduced the secretion of Aβ40/42 peptides, suggesting that estrogen replacement therapy may protect women against the development of AD by regulating βAPP metabolism. Increasing evidence indicates that testosterone, especially bioavailable testosterone, decreases with age in older men and in postmenopausal women. We report here that treatment with testosterone increases the secretion of the nonamyloidogenic APP fragment, sβAPPα, and decreases the secretion of Aβ peptides from N2a cells and rat primary cerebrocortical neurons. These results raise the possibility that testosterone supplementation in elderly men may be protective in the treatment of AD.

Recent work has highlighted the tumor microenvironment as a central player in cancer. In particular, interactions between tumor and immune cells may help drive the development of brain tumors such as glioblastoma multiforme (GBM). Despite significant research into the molecular classification of glioblastoma, few studies have characterized in a comprehensive manner the immune infiltrate in situ and within different GBM subtypes.In this study, we use an unbiased, automated immunohistochemistry-based approach to determine the immune phenotype of the four GBM subtypes (classical, mesenchymal, neural and proneural) in a cohort of 98 patients. Tissue Micro Arrays (TMA) were stained for CD20 (B lymphocytes), CD5, CD3, CD4, CD8 (T lymphocytes), CD68 (microglia), and CD163 (bone marrow derived macrophages) antibodies. Using automated image analysis, the percentage of each immune population was calculated with respect to the total tumor cells. Mesenchymal GBMs displayed the highest percentage of microglia, macrophage, and lymphocyte infiltration. CD68⁺ and CD163⁺ cells were the most abundant cell populations in all four GBM subtypes, and a higher percentage of CD163⁺ cells was associated with a worse prognosis. We also compared our results to the relative composition of immune cell type infiltration (using RNA-seq data) across TCGA GBM tumors and validated our results obtained with immunohistochemistry with an external cohort and a different method. The results of this study offer a comprehensive analysis of the distribution and the infiltration of the immune components across the four commonly described GBM subgroups, setting the basis for a more detailed patient classification and new insights that may be used to better apply or design immunotherapies for GBM.

BACKGROUND. The endoscopic, endonasal, extended transsphenoidal approach is a minimal-access technique for managing craniopharyngiomas. Outcome measures