Mesenchymal Stem Cells-derived Exosomes Ameliorate Lupus by Inducing M2 Macrophage Polarization and Regulatory T Cell Expansion in MRL/lpr Mice.

ABSTRACT

Previous studies have implicated that the transplantation of human umbilical cord mesenchymal stem cells (hUC-MSCs) effectively alleviates systemic lupus erythematosus (SLE) primarily due to immunomodulatory effects. However, little is known about the role of hUC-MSC-derived exosomes in SLE. This study is carried out to investigate the modifying effects of hUC-MSC-exosomes on the differentiation and function of immune cells in SLE. hUC-MSC-derived exosomes were extracted from the cultural supernatant of hUC-MSCs by ultrahigh speed centrifugation. Quantitative real-time polymerase chain reaction, western blot, enzyme-linked immunosorbent assay, and flow cytometry were performed to estimate the effect of hUC-MSC-derived exosomes on macrophage and regulatory T cell (Treg) polarization. In vivo, hUC-MSC-exosomes were injected intravenously into 28-week-old MRL/lpr mice. We had found that exosomes derived from hUC-MSC restrained the proliferation and inflammation of macrophages in vitro. Besides, MSC-exosomes inhibited CD68+M1 and HLA-DR+M1 but promoted CD206+M2 and CD163+M2 in vitro. Moreover, MRL/lpr mice administrated by intravenous injection of MSC-exosomes had less infiltration of CD14+CD11c+M1 cells but more CD14+CD163+M2 cells as well as Tregs in spleens compared with those in MRL/lpr mice treated by PBS. Additionally, MSC-exosomes could alleviate nephritis, liver and lung injuries of MRL/lpr mice. The survival of lupus mice could be improved after MSC-exosome treatment. This study has suggested that MSC-derived exosomes exert anti-inflammatory and immunomodulatory effects in SLE. MSC-exosomes ameliorate nephritis and other key organ injuries by inducing M2 macrophages and Tregs polarization. As natural nanocarriers, MSC-exosomes may serve as a promising cell-free therapeutic strategy for SLE.Abbreviations SLE Systemic lupus erythematosus; hUC-MSCs Human umbilical cord mesenchymal stem cells; MSCs Mesenchymal stem cells; qRT-PCR Quantitative real-time polymerase chain reaction; ELISA Enzyme-linked immunosorbent assay; Tregs Regulatory cells; TNF-α Tumor necrosis factor alfa; IL Interleukin; COVID-19 Coronavirus disease 2019; pTHP-1 PMA-induced THP-1 macrophages; TEM Transmission electron microscopy; LPS Lipopolysaccharide; EVs Extracellular vesicles; TRAF1 Tumor necrosis factor receptor-associated factor 1; IRAK1 Interferon-α-interleukin-1 receptor-associated kinase 1; NF-κB Nuclear factor-κB; BLyS B lymphocyte stimulator; APRIL A proliferation-inducing ligand.