While glia-derived exosomes have been extensively studied in heatstroke induced brain injury, the role of exosomal microRNAs (miRNAs) secreted by astrocyte remains underexplored. In this study, the viability of C8-D1A cells decreased after heat stress, apoptosis rate and the expression levels of proinflammatory cytokines such as TNF-α, IL-6, IL-1α and IL-1β increased to different degrees. The extracellular vesicles obtained by ultracentrifugation were identified via transmission electron microscopy (TEM), nanoparticle tracking technology Nanoparticle tracking analysis, and nanoflow cytometry (nanoFCM), which was consistent with the characterization of the exosomes. In the following sections, the collected EVs will be referred to as exosome-enriched preparations. Exosome-enriched preparations’s miRNA sequencing identified 23 differentially expressed miRNAs. Further functional analysis via gene ontology enrichment revealed that 46 genes regulated cell death and that 38 genes were involved in neuronal apoptosis. Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis revealed that the main enriched signalling pathways were involved in biological processes such as apoptosis, inflammation, and oxidative stress. Among them, miR-712-3p was the most upregulated miRNA in the heat stress group. MiR-712-3p was overexpressed and inhibited by intranasal administration in vivo and cell transfection in vitro , and it was found that miR-712-3p could reduce brain injury and improve neuronal activity under heat stress. Moreover, RNA sequencing of neurons and transmission electron microscopy revealed that miR-712-3p can affect lysosomal function. Differential expressed genes can be involved in specific lysosome-related processes, and we predicted Atp6v1c1 associated with miR-712-3p as a candidate gene through the miRDB database. Collectively, our findings demonstrate that miR-712-3p ameliorates heat stroke-induced brain injury, with this protective effect being linked to the modulation of neuronal lysosomal function. Furthermore, the study confirms the involvement of astrocyte-derived exosome-enriched preparations in mediating this protective effect in vitro .
Chen et al. (Wed,) studied this question.