Plasma exosomal miRNAs involved in endothelial injury in microscopic polyangiitis patients.

Microscopic polyangiitis (MPA) is a systemic autoimmune disease that primarily affects the small and medium blood vessels. Endothelial injury is one of the pathological hallmarks of MPA. However, the pathogenesis for this has not yet been fully elucidated. Exosomal microRNAs (miRNAs) have recently emerged as a new molecular pattern involved in the endothelial injury in other diseases. Hence, we speculated that MPA plasma-derived exosomes (MPA-exo) could induce the endothelial injury, which was likely to be aroused by the dysregulated exosomal miRNAs in MPA. In the present study, plasma-derived exosomes were isolated and identified. MPA-exo could be internalized by human renal glomerular endothelial cells (HRGECs) in vitro and induced HRGECs injury. Subsequently, a series of differentially expressed miRNAs in MPA-exo were identified by high-throughput sequencing analysis. Further bioinformatics analysis for the target genes of these differentially expressed miRNAs showed a potential mechanism for their possible role in MPA endothelial injury. Notably, we revealed a considerable correlation between miR-185-3p, miR-125a-3p, and clinical parameters. In conclusion, the current study revealed that differentially expressed miRNAs in MPA-exo are associated with the endothelial injury. Our results suggested that these miRNAs and their target genes might be involved in the inflammation process of MPA.

STAT3/HIF-1α/fascin-1 axis promotes RA FLSs migration and invasion ability under hypoxia.

Rheumatoid arthritis (RA) synovium was identified as "tumor-like" tissues because of the hypoxic microenvironment, significant cell proliferation, and invasion phenotypes. It was reported that hypoxia promoted tumor aggressiveness via up-regulated expression of fascin-1 in cancer. However, the role of fascin-1 in RA synovial hyperplasia and joint injury progression remains unknown. In the current study, we first identified that both fascin-1 and HIF-1α were highly expressed in the RA synovium, in which they were widely colocalized, compared to osteoarthritis(OA). As well, levels of fascin-1 in RA fibroblast-like synoviocytes(FLSs) were found significantly higher than those in OA FLSs. Further, it was demonstrated that the mRNA and protein levels of fascin-1 in RA FLSs were up-regulated in hypoxia (3 % O2) and experimental hypoxia induced by cobalt chloride. Mechanistically, the HIF-1α-mediated hypoxia environment activated the gene expression of the fascin-1 protein, which in turn promoted the migration and invasion of RA FLSs. Accordingly, the restoration of FLSs migration and invasion was observed following siRNA-mediated silencing of fascin-1 and HIF-1α expression. Notably, under the experimental hypoxia, we found that the expression levels of fascin-1, HIF-1α, and p-STAT3 were increased in a time-dependent manner, and fascin-1and HIF-1α expressions were dependent on p-STAT3. Our results indicated that hypoxia-induced fascin-1 up-regulation promoted RA FLSs migration and invasion through the STAT3/HIF-1α/fascin-1 axis, which might represent a novel therapeutic target for the treatment of RA.