Defective neutrophil-derived exosomes induce macrophage activation through miR-122-5p in Behçet’s Disease

Background Behçet’s disease (BD) is a life-threatening systemic vasculitis characterized by polymorphonuclear neutrophil (PMN) and macrophage activation. This study aimed to elucidate the potential dysregulation of BD PMN exosomes on macrophage activation. Methods BD PMN exosomes were isolated, quantified, incubated with macrophages, and analyzed by miRNA sequencing (n=4). RNA sequencing of miRNA-transfected macrophages (n=6) was analyzed using transcription factor co-regulation network and miRNA target prediction to identify key regulatory factors, which were validated by dual luciferase reporter assay and miRNA/siRNA transfection. Results BD PMN exosomes were decreased and negatively correlated with CRP. PMN exosomes suppressed IL-6, TNF-α, CD80 and CD86 expressions on macrophages, which were attenuated in BD PMN exosomes. miRNA sequencing showed decreased miR-122-5p in BD PMN exosomes, which targeted IRF5, suppressed TLR4 signaling and IFN-β autocrine, and downregulated macrophage activation. Conclusions BD PMN exosomes were decreased in both quantity and miR-122-5p, which impaired the immunoregulatory potential on macrophages through degrading IRF5 and suppressing IFN-β autocrine, indicating a new interaction mechanism between PMNs and macrophages.