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Exosomes derived from chondroitin sulfate proteoglycan (CSPG) 4 type neural precursor cells (CSPG4Es) were purified from human plasma by sequential immunoabsorption with anti-CSPG4 and anti–platelet growth factor receptor α mAb to characterize the potential in vivo roles of CSPG4 cells in neuronal repair. Hepatocyte growth factor, fibroblast growth factors (FGFs)-2 and -13, and type 1 insulin-like growth factor (IGF-1), which enhance neuronal survival and functions, were quantified in CSPG4E extracts. For CSPG4Es of 24 healthy control subjects, mean levels of hepatocyte growth factor, FGF-13, and IGF-1, but not FGF-2, were significantly higher by up to 7-fold than in their neuronal-derived exosomes, and mean levels of all 4 growth factors were significantly higher by up to 8-fold than in their astrocyte-derived exosomes. Mean CSPG4E levels of all growth factors were significantly lower in patients with mild Alzheimer disease (AD) (n = 24) than in age- and sex-matched cognitively normal control subjects (n = 24). Mean CSPG4E levels of all growth factors were also significantly lower in 15 patients at the stage of moderate dementia from AD (AD(2)) and at their preclinical stage 3 to 8 yr earlier (AD(1)), with no differences between values at stages AD(1) and AD(2). Current findings suggest that CSPG4 cells export in exosomes higher levels of neurotrophic factors than neurons or astrocytes and that CSPG4E neurotrophic factors are diminished early in AD, with no significant progression of decreases later in the course.—Goetzl, E. J., Nogueras-Ortiz, C., Mustapic, M., Mullins, R. J., Abner, E. L., Schwartz, J. B., Kapogiannis, D. Deficient neurotrophic factors of CSPG4-type neural cell exosomes in Alzheimer disease.

Interactions of the presynaptic proteins, neuronal pentraxin 2 (NPTX2) and neurexin 2α (NRXN2α), with their respective postsynaptic functional partners, GluA4-containing glutamate (AMPA4) receptor and neuroligin 1 (NLGN1), enhance excitatory synaptic activity in some areas of the hippocampus and cerebral cortex. As early damage of such excitatory circuits in the brain tissues of participants with Alzheimer's disease (AD) correlates with cognitive losses, plasma neuron-derived exosome (NDE) levels of these 2 pairs of specialized synaptic proteins were quantified to assess their biomarker characteristics. The NDE contents of all 4 proteins were decreased significantly in AD dementia ( n = 46), and diminished levels of AMPA4 and NLGN1 correlated with the extent of cognitive loss. In a preclinical period, 6-11 yr before the onset of dementia, the NDE levels of all but NPTX2 were significantly lower than those of matched controls, and levels of all proteins declined significantly with the development of dementia. Reductions in NDE levels of these specialized excitatory synaptic proteins may therefore be indicative of the extent of cognitive loss and may reflect progression of the severity of AD.-Goetzl, E. J., Abner, E. L., Jicha, G. A., Kapogiannis, D., Schwartz, J. B. Declining levels of functionally specialized synaptic proteins in plasma neuronal exosomes with progression of Alzheimer's disease.

Plasma endothelial cell-derived exosomes (EDEs) and platelet-derived exosomes (PDEs) were precipitated and enriched separately by immunospecific absorption procedures for analyses of cargo proteins relevant to atherosclerosis. EDEs had usual exosome size and marker protein content, and significantly higher levels than PDEs of the endothelial proteins vascular cell adhesion molecule-1 (VCAM-1) and endothelial nitric oxide synthase, whereas PDEs had significantly higher levels of platelet glycoprotein VI. EDE levels of VCAM-1, von Willebrand factor, platelet-derived growth factor (PDGF)-BB, angiopoietin-1, and lysyl oxidase-2 and the cerebrovascular-selective proteins glucose transporter 1, permeability-glycoprotein, and large neutral amino acid transporter 1 were significantly higher for 18 patients with cerebrovascular disease (CeVD) than for 18 age- and gender-matched control subjects. PDE levels of PDGF-AA, platelet glycoprotein VI, integrin-linked kinase-1, high mobility group box-1 protein, chemokine CXCL4, and thrombospondin-1 were significantly higher in patients with CeVD than in control subjects, but differences were less with greater overlaps than for EDE proteins. EDE levels of Yes-associated protein (YAP) were higher and of P(S127)-YAP lower in patients with CeVD than in control subjects, consistent with heightened activity of this mechanical force-sensitive system in atherosclerosis. Elevated EDE and PDE levels of atherosclerosis-promoting proteins in CeVD justify clinical studies of their potential value as biomarkers.-Goetzl, E. J., Schwartz, J. B., Mustapic, M., Lobach, I. V., Daneman, R., Abner, E. L., Jicha, G. A. Altered cargo proteins of human plasma endothelial cell-derived exosomes in atherosclerotic cerebrovascular disease.

Efficient intercellular transfer of RNAs, proteins, and lipids as protected exosomal cargo has been demonstrated in the CNS, but distinct physiologic and pathologic roles have not been well defined for this pathway. The capacity to isolate immunochemically human plasma neuron-derived exosomes (NDEs), containing neuron-specific cargo, has permitted characterization of CNS-derived exosomes in living humans. Constituents of the amyloid β-peptide (Aβ)42-generating system now are examined in 2 distinct sets of human neural cells by quantification in astrocyte-derived exosomes (ADEs) and NDEs, enriched separately from plasmas of patients with Alzheimer's disease (AD) or frontotemporal dementia (FTD) and matched cognitively normal controls. ADE levels of β-site amyloid precursor protein-cleaving enzyme 1 (BACE-1), γ-secretase, soluble Aβ42, soluble amyloid precursor protein (sAPP)β, sAPPα, glial-derived neurotrophic factor (GDNF), P-T181-tau, and P-S396-tau were significantly (3- to 20-fold) higher than levels in NDEs for patients and controls. BACE-1 levels also were a mean of 7-fold higher in ADEs than in NDEs from cultured rat type-specific neural cells. Levels of BACE-1 and sAPPβ were significantly higher and of GDNF significantly lower in ADEs of patients with AD than in those of controls, but not significantly different in patients with FTD than in controls. Abundant proteins of the Aβ42 peptide-generating system in ADEs may sustain levels in neurons. ADE cargo proteins may be useful for studies of mechanisms of cellular interactions and effects of BACE-1 inhibitors in AD.-Goetzl, E. J., Mustapic, M., Kapogiannis, D., Eitan, E., Lobach, I. V., Goetzl, L., Schwartz, J. B., Miller, B. L. Cargo proteins of plasma astrocyte-derived exosomes in Alzheimer's disease.

Insulin resistance causes diminished glucose uptake in similar regions of the brain in Alzheimer’s disease (AD) and type 2 diabetes mellitus (DM2). Brain tissue studies suggested that insulin resistance is caused by low insulin receptor signaling attributable to its abnormal association with more phospho (P)-serine-type 1 insulin receptor substrate (IRS-1) and less P-tyrosine-IRS-1. Plasma exosomes enriched for neural sources by immunoabsorption were obtained once from 26 patients with AD, 20 patients with DM2, 16 patients with frontotemporal dementia (FTD), and matched case control subjects. At 2 time points, they were obtained from 22 others when cognitively normal and 1 to 10 yr later when diagnosed with AD. Mean exosomal levels of extracted P-serine 312-IRS-1 and P-pan-tyrosine-IRS-1 by ELISA and the ratio of P-serine 312-IRS-1 to P-pan-tyrosine-IRS-1 (insulin resistance factor, R) for AD and DM2 and P-serine 312-IRS-1 and R for FTD were significantly different from those for case control subjects. The levels of R for AD were significantly higher than those for DM2 or FTD. Stepwise discriminant modeling showed correct classification of 100% of patients with AD, 97.5% of patients with DM2, and 84% of patients with FTD. In longitudinal studies of 22 patients with AD, exosomal levels of P-serine 312-IRS-1, P-pan-tyrosine-IRS-1, and R were significantly different 1 to 10 yr before and at the time of diagnosis compared with control subjects. Insulin resistance reflected in R values from this blood test is higher for patients with AD, DM2, and FTD than case control subjects; higher for patients with AD than patients with DM2 or FTD; and accurately predicts development of AD up to 10 yr prior to clinical onset.—Kapogiannis, D., Boxer, A., Schwartz, J. B., Abner, E. L., Biragyn, A., Masharani, U., Frassetto, L., Petersen, R. C., Miller, B. L., Goetzl, E. J. Dysfunctionally phosphorylated type 1 insulin receptor substrate in neural-derived blood exosomes of preclinical Alzheimer’s disease.

A role for adenosine in immunosenescence was investigated in T cells from older (≥65 yr) and younger (24–45 yr) healthy humans. Adenosine concentrations in cultures of activated T cells were significantly higher (P

Cytokine generation by T cells and monocytes was determined for 50 subjects aged 65 yr or older and concurrently studied young subjects individually matched to each old subject for sex, race, and national origin. Highly significant differences between cytokine levels of old and young subjects all were gender specific. For T cells stimulated with anti-CD3 plus anti-CD28 antibodies, mean ratios of IFN-γ generation for healthy old to young subjects were 0.22 for men (P