Exosomal miR-155 from M1-polarized macrophages promotes EndoMT and impairs mitochondrial function via activating NF-κB signaling pathway in vascular endothelial cells after traumatic spinal cord injury

Abstract

Pathologically, blood-spinal-cord-barrier (BSCB) disruption after spinal cord injury (SCI) leads to infiltration of numerous peripheral macrophages into injured areas and accumulation around newborn vessels. Among the leaked macrophages, M1-polarized macrophages are dominant and play a crucial role throughout the whole SCI process. The aim of our study was to investigate the effects of M1-polarized bone marrow-derived macrophages (M1-BMDMs) on vascular endothelial cells and their underlying mechanism. Microvascular endothelial cell line bEnd.3 cells were treated with conditioned medium or exosomes derived from M1-BMDMs, followed by evaluations of endothelial-to-mesenchymal transition (EndoMT) and mitochondrial function. After administration, we found conditioned medium or exosomes from M1-BMDMs significantly promoted EndoMT of vascular endothelial cells in vitro and in vivo , which aggravated BSCB disruption after SCI. In addition, significant dysfunction of mitochondria and accumulation of reactive oxygen species (ROS) were also detected. Furthermore, bioinformatics analysis demonstrated that miR-155 is upregulated in both M1-polarized macrophages and microglia. Experimentally, exosomal transfer of miR-155 participated in M1-BMDMs-induced EndoMT and mitochondrial ROS generation in bEnd.3 cells, and subsequently activated the NF-κB signaling pathway by targeting downstream suppressor of cytokine signaling 6 (SOCS6), and suppressing SOCS6-mediated p65 ubiquitination and degradation. Finally, a series of rescue assay further verified that exosomal miR155/SOCS6/p65 axis regulated the EndoMT process and mitochondrial function in vascular endothelial cells. In summary, our work revealed a potential mechanism describing the communications between macrophages and vascular endothelial cells after SCI which could benefit for future research and aid in the development of potential therapies for SCI.

Extracellular vesicles derived from melatonin‐preconditioned mesenchymal stem cells containing USP29 repair traumatic spinal cord injury by stabilizing NRF2

“…Numerous studies have focused on the relationship between microglia/macrophages polarization and changes in mitochondrial function. [37][38][39] We, therefore, examined the change in levels of LPS-induced reactive oxygen species (ROS), which is another characteristic of M1-like microglia/macrophages. Both EVs and MEVs markedly reduced ROS levels in BV2 microglia, but the effect of MEVs was larger (Figure 4F,G).…”

“…A Seahorse XF96 Metabolic Flux Analyzer (Seahorse Biosciences) was used to measure OCR as previously described. 39 OCR was evaluated by sequential addition of the ATP synthase blocker oligomycin (2 μmol/L), the mitochondrial uncoupler carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (1 μmol/L, and the complex I and III inhibitors antimycin A (1 μmol/L) and rotenone (1 μmol/L). XFe Wave software (Seahorse Biosciences) was used to quantify data and calculate basal respiration, ATP production, respiratory capacity (maximal electron transport chain activity), and respiratory reserve (flexibility with increased energy demand), according to the manufacturer's protocol.…”

Emerging Exosomes and Exosomal MiRNAs in Spinal Cord Injury

“…These studies demonstrated that the miR-155/SOCS6/p65 axis can upregulate the ROS level in the microvascular endothelial cell line (bEnd.3 cells) and lead to significant mitochondrial dysfunction. This research revealed a new method for maintaining BSCB integrity after SCI (Ge et al, 2021). The pro-inflammatory cytokines TNFα and interleukin (IL)-1β could upregulate some miRs (miR-145-5p, miR-24-3p, miR-214-3p, miR-206, and miR-34c-5p) and downregulate other miRs (miR-451a, miR-29b-3p, and miR-21-5p).…”

Exosomes as mediators of intercellular crosstalk in metabolism

“…Other studies in human and mouse macrophages have supported a role for M1-like macrophage-derived exosomes in promoting macrophage proinflammatory pathways. For example, in both human and mouse macrophage exosomes, miR-155 has been identified as a potent pro-inflammatory factor by repressing the expression of PPARg, Socs1, or Socs6 (O'Connell et al, 2007;Ying et al, 2017;Wang et al, 2017;Ge et al, 2021). Chen et al showed that LPS stimulation of the human macrophage THP-1 cell line leads to the release of exosomes that can activate the stellate cell fibrogenic program, and they implicated miR-103-3p in this process (Chen et al, 2020b).…”