Activated human astrocyte‐derived extracellular vesicles modulate neuronal uptake, differentiation and firing

Abstract

Astrocytes in the central nervous system (CNS) provide supportive neural functions and mediate inflammatory responses from microglia. Increasing evidence supports their critical roles in regulating brain homoeostasis in response to pro-inflammatory factors such as cytokines and pathogen/damage-associated molecular pattern molecules in infectious and neurodegenerative diseases. However, the underlying mechanisms of the trans-cellular communication are still unclear. Extracellular vesicles (EVs) can transfer a large diversity of molecules such as lipids, nucleic acids and proteins for cellular communications. The purpose of this study is to characterize the EVs cargo proteins derived from human primary astrocytes (ADEVs) under both physiological and pathophysiological conditions. ADEVs were isolated from human primary astrocytes after vehicle (CTL) or interleukin-1β (IL-1β) pre-treatment. Label-free quantitative proteomic profiling revealed a notable up-regulation of proteins including actin-associated molecules, integrins and major histocompatibility complex in IL-1β-ADEVs compared to CTL-ADEVs, which were involved in cellular metabolism and organization, cellular communication and inflammatory response. When fluorescently labelled ADEVs were added into primary cultured mouse cortical neurons, we found a significantly increased neuronal uptake of IL-1β-ADEVs compared to CTL-ADEVs. We further confirmed it is likely due to the enrichment of surface proteins in IL-1β-ADEVs, as IL-1β-ADEVs uptake by neurons was partially suppressed by a specific integrin inhibitor. Additionally, treatment of neurons with IL-1β-ADEVs also reduced neurite outgrowth, branching and neuronal firing. These findings provide insight for the molecular mechanism of the ADEVs' effects on neural uptake, neural differentiation and maturation, and its alteration in inflammatory conditions.

Extracellular Vesicles as Signaling Mediators and Disease Biomarkers across Biological Barriers

“…While the mechanisms that mediate the biological effects of EVs on their cellular targets remain poorly known, it is clear that EVs are implicated in most, if not all, physiopathological processes, including signal transduction, cell growth, and differentiation, metabolic regulation, embryofetal development, organogenesis, tissue homeostasis and repair/regeneration, antigen presentation and immune response, ageing, pathogen-host interactions, carcinogenesis, tumor invasion/metastasis, cardiovascular dysfunction, etc. [9,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. The EV cargo, packaged within relatively stable membrane-bound structures, is sheltered from degradation by the extracellular enzymes present in biological fluids, and may therefore maintain biological stability over comparatively long periods of time [38].…”

Human ESC‐sEVs alleviate age‐related bone loss by rejuvenating senescent bone marrow‐derived mesenchymal stem cells

“…Previous studies reported that EVs can affect the biological behaviours of recipient cells by transferring the encapsulated proteins [34,35]. Therefore, we prepared proteins from hESC-sEVs (Supplementary Figure 5), and then performed LC-MS/MS analysis to identify the protein contents of hESC-sEVs.…”

The Function of Astrocyte Mediated Extracellular Vesicles in Central Nervous System Diseases

“…The brain is capable to communicate with the rest of the body via transporting EVs to communicate healthy and disease states of the body (Gomez-Molina et al, 2019). Study of exosomes could increase our knowledge of astrocytes, their homeostasis, and metabolic regulating mechanisms since they are capable of transferring biological molecules from one cell to another (Fruhbeis et al, 2013;Silverman et al, 2019;Upadhya et al, 2020;You et al, 2020). Interestingly, miRNAs contained in the exosomes secreted by mouse astrocytes were different from the miRNAs that originally existed in mouse astrocytes.…”

“…Physical or chemical microenvironmental changes affect astrocytes' growth and behavior. Changes in astrocytes alter the type of signals they release, therefore altering the microenvironment in a positive or negative manner (Paolicelli et al, 2019;Schiera et al, 2019;You et al, 2020). A study found a novel brain penetrant inhibitor that inhibited the release of vesicles in astrocytes (Rojas et al, 2019).…”

“…Exosomes attenuated the inflammation by inhibiting the CXCL1 in astrocytes (Song et al, 2019). Interestingly, activated human astrocyte-derived EVs modulate neuronal uptake, differentiation, and firing (You et al, 2020). Astrocytes-derived EVs enriched IL-1β lower neurite development and maturation during neuroinflammation (You et al, 2020).…”