The Role of miR-30d-5p in Neutrophil-Derived Exosomes in Promoting Systemic Lupus Erythematosus.

Background: In this study, we investigated the role of neutrophil-derived exosomal miR-30d-5p in systemic lupus erythematosus (SLE). Methods: We extracted exosomes from the neutrophils collected from SLE patients and healthy donors and analyzed the relative level of miR-30d-5p. The exosomes were characterized by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). We mimicked SLE using MRL/lpr mice and treated the mice with exosomes and miR-30d-5p inhibitors. The RNA level of miR-30d-5p in serum of mice was analyzed by qPCR. The images of spleen were captured to evaluate splenomegaly. The serum levels of anti-nuclear antibodies (ANAs), total IgG, total IgM, and anti-dsDNA IgG were measured by ELISA. The kidney injury was analyzed by albumin level, haematoxylin and eosin (HE) staining, active index, and chronic index. The T cell differentiation and B cell activation were detected by flow cytometry. For T follicular helper (TfH) cell analysis, cells were stained with anti-CXCR5 and anti-PD-1 antibodies. Levels of inflammatory cytokines in serum were measured by ELISA. Results: The exosomes from SLE patients showed significant higher level of miR-30d-5p. Treatment with neutrophil-exosomes enhanced the degree of splenomegaly in MRL/lpr mice and production of anti-nuclear antibodies (ANAs), total IgG, total IgM, and anti-dsDNA IgG, which was repressed by miR-30d-5p inhibitor. Compared with MRL/lpr mice, mice treated with neutrophil-derive exosomes exhibited a notable increase of proteinuria and infiltration of lymphocytes in kidney, whereas inhibition of miR-30d-5p reduced this elevation. Exosome treatment elevated the number of IL17+ Th17 cells, CXCR5+PD-1+ TfH cells, reduced the portion of Foxp3+ Treg cells, and elevated B cells, and inhibition of miR-30d-5p reversed these effects. Conclusion: The neutrophils from SLE exhibited higher level of miR-30d-5p, and inhibition of miR-30d-5p could suppress the T cell and B cell activation, reduce inflammatory cytokine and antibodies production, and alleviate the lupus nephritis during SLE.