LncRNA MIAT enhances systemic lupus erythematosus by upregulating CFHR5 expression via miR-222 degradation

Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Complement factor H related protein 5 (CFHR5) may contribute to dysfunctional complement activation, thus predisposing to SLE. The expression levels of anti-dsDNA, C3 and CFHR5 in blood samples from 50 SLE patients and 50 healthy individuals were evaluated, and also their expression levels were measured in an MRL/lpr mouse model and control MRL/MPJ mice. The results showed that CFHR5 expression increased in SLE patients together with the increase of anti-dsDNA in comparison with the healthy control. Furthermore, CFHR5 expression was inversely correlated with C3, down-regulation of which was associated with worse SLE. Previous studies indicated that long noncoding RNA (lncRNA) regulates mRNA synthesis via microRNA (miRNA) inhibition. The present bioinformatics analysis revealed that the target miRNA (miR-222) was combined with both lncRNA MIAT and mRNA CFHR5. H&E staining of the kidney tissues of the MRL/lpr mice revealed that lncRNA MIAT, as a competitive inhibitor of miR-222, enhanced SLE by upregulating CFHR5 expression through the degradation of miR-222 in vivo. Thus, our study revealed for the first time the role of lncRNA MIAT in regulating CFHR5 expression in SLE in vivo and provided new insights into the role of lncRNA in regulation and complement function of SLE pathogenesis.