M1-type microglia-derived exosomes contribute to blood–brain barrier damage

As a key substance for intercellular communication, exosomes could be a potential strategy for stroke treatment. Activated microglia disrupt the integrity of blood–brain barrier (BBB) to facilitate the stroke process. Hence, this study was designed to investigate the effect of microglia-derived exosomes on BBB cell model injury and to explore the underlying molecular mechanisms. M1 polarization of BV2 cells was induced with LPS and their derived exosomes were isolated. Astrocytes were cultured in primary culture and constructed with End3 cells as a BBB cell model. After co-culture with exosomes, the BBB cell model was examined for changes in TEER, permeability, and expression of BBB-related proteins (Claudin-1, Occludin, ZO-1 and JAM). Resting and M1-type BV2 cell-derived exosomes perform small RNA sequences and differentially expressed miRNAs (DE-miRNAs) are identified by bioinformatics. M1-type BV2 cell-derived exosomes decreased End3 cell viability, and increased their apoptotic ratio. Moreover, M1 type BV2 cell-derived exosomes dramatically enhanced the permeability of BBB cell model, and diminished the TEER and BBB-related protein (Claudin-1, Occludin, ZO-1) expression. Notably, resting BV2 cell-derived exosomes had no effect on the integrity of BBB cell model. Sequencing results indicated that 71 DE-miRNAs were present in M1 BV2 cell-derived exosomes, and their targets mediated neurological development and signaling pathways such as MAPK and cAMP. RT-qPCR confirmed the differential expression of mmu-miR-125a-5p, mmu-miR-122b-3p, mmu-miR-139-3p, mmu-miR-330-3p, mmu-miR-3057-5p and mmu-miR-342-3p consistent with the small RNA sequence. Furthermore, Creb1, Jun, Mtor, Frk, Pabpc1 and Sdc1 are the most well-connected proteins in the PPI network. M1-type microglia-derived exosomes contribute to the injury of BBB cell model, which has the involvement of miRNAs. Our findings provide new perspectives and potential mechanisms for future M1 microglia-derived exosomes as therapeutic targets in stroke.