Exosomes in Alzheimer's disease

Dipeptidyl Vinyl Sulfone as a Novel Chemical Tool to Inhibit HMGB1/NLRP3-Inflammasome and Inflamma-miRs in Aβ-Mediated Microglial Inflammation

Rapid microglial activation and associated inflammatory pathways contribute to immune-defense and tissue repair in the central nervous system (CNS). However, persistent activation of these cells will ultimately result in vast production of pro-inflammatory mediators and other neurotoxic factors, which may induce neuronal damage and contribute to chronic neurodegenerative diseases, as Alzheimer's disease (AD). Therefore, small molecules with immunomodulatory effects on microglia may be considered as potential tools to counteract their proinflammatory phenotype and neuroimmune dysregulation in such disorders. Indeed, reducing amyloid-β (Aβ)-induced microglia activation is believed to be effective in treating AD. In this study, we investigated whether dipeptidyl vinyl sulfone (VS) was able to attenuate Aβ-mediated inflammatory response using a mouse microglial (N9) cell line and a solution containing a mixture of Aβ aggregates. We show that low levels of VS are able to prevent cell death while reducing microglia phagocytosis upon Aβ treatment. VS also suppressed Aβ-induced expression of inflammatory mediators in microglia, such as matrix metalloproteinase (MMP)-2 and MMP-9, as well as high-mobility group box protein-1 (HMGB1), nod-like receptor protein 3 (NLRP3)-inflammasome, and interleukin (IL)-1β. Interestingly, increased expression of the two critical inflammation-related microRNAs (miR)-155 and miR-146a in microglia upon Aβ treatment was also prevented by VS coincubation. Taken together, VS emerges as a potential new therapeutic strategy worthy of further investigation in improved cellular and animal models of AD.

Increased Release of Apolipoprotein E in Extracellular Vesicles Following Amyloid-β Protofibril Exposure of Neuroglial Co-Cultures

Extracellular vesicles (EVs), including exosomes and larger microvesicles, have been implicated to play a role in several conditions, including Alzheimer's disease (AD). Since the EV content mirrors the intracellular environment, it could contribute with important information about ongoing pathological processes and may be a useful source for biomarkers, reflecting the disease progression. The aim of the present study was to analyze the protein content of EVs specifically released from a mixed co-culture of primary astrocytes, neurons, and oligodendrocytes treated with synthetic amyloid-β (Aβ42) protofibrils. The EV isolation was performed by ultracentrifugation and validated by transmission electron microscopy. Mass spectrometry analysis of the EV content revealed a total of 807 unique proteins, of which five displayed altered levels in Aβ42 protofibril exposed cultures. The most prominent protein was apolipoprotein E (apoE), and by western blot analysis we could confirm a threefold increase of apoE in EVs from Aβ42 protofibril exposed cells, compared to unexposed cells. Moreover, immunoprecipitation studies demonstrated that apoE was primarily situated inside the EVs, whereas immunocytochemistry indicated that the EVs most likely derived from the astrocytes and the neurons in the culture. The identified Aβ-induced sorting of apoE into EVs from cultured neuroglial cells suggests a possible role for intercellular transfer of apoE in AD pathology and encourage future studies to fully elucidate the clinical relevance of this event.

Blood-based biomarkers in Alzheimer disease: Current state of the science and a novel collaborative paradigm for advancing from discovery to clinic

The last decade has seen a substantial increase in research focused on the identification of blood-based biomarkers that have utility in Alzheimer's disease (AD). Blood-based biomarkers have significant advantages of being time- and cost-efficient as well as reduced invasiveness and increased patient acceptance. Despite these advantages and increased research efforts, the field has been hampered by lack of reproducibility and an unclear path for moving basic discovery toward clinical utilization. Here we reviewed the recent literature on blood-based biomarkers in AD to provide a current state of the art. In addition, a collaborative model is proposed that leverages academic and industry strengths to facilitate the field in moving past discovery only work and toward clinical use. Key resources are provided. This new public-private partnership model is intended to circumvent the traditional handoff model and provide a clear and useful paradigm for the advancement of biomarker science in AD and other neurodegenerative diseases.