MicroRNA-409-3p regulates macrophage migration in polymyositis through targeting CXCR4.

BACKGROUND

Macrophage migration and infiltration contribute to the pathogenesis of polymyositis (PM). This study aims to investigate the effect and underlying mechanism of miR-409-3p on macrophage migration in PM.

METHODS

The GSE143845 database was used to predict the altered expression of microRNAs (miRNAs) in PM. The quantitative real-time PCR (qRT-PCR), western blot and Transwell assay were performed to detect migration of macrophages and expressions of related molecules. A luciferase activity assay was conducted to confirm the binding of miR-409-3p and CXCR4 3'-UTR. Next, a mouse model of experimental autoimmune myositis (EAM) was established. Haematoxylin and eosin (HE) staining, immunohistochemistry (IHC), and enzyme-linked immunosorbent assay (ELISA) were used to measure associated factors.

RESULTS

MiR-409-3p was downregulated in PM of GSE143845 database and patients. Differently, the serum creatine kinase (s-CK), TNF-α, and IL-6 in patients with PM were increased. Furthermore, miR-409-3p mimic transfection reduced the migration of macrophages and CXCR4 levels, while miR-409-3p inhibitor exerted the opposite effects. CXCR4 was a target of miR-409-3p, and the effect of CXCR4 on promoting macrophage migration was reversed by miR-409-3p mimic. In vivo, miR-409-3p agomir injection reduced inflammatory cells, macrophages, and TNFα and IL-6 levels in muscles and serum of EAM mouse models.

CONCLUSIONS

In conclusion, miR-409-3p reduces the migration of macrophages through negatively regulating CXCR4 expression in PM.