MicroRNAs (miRNAs, miRs) are small non-coding RNAs that mainly function in the post-transcriptional regulation of genes. miRNA that is secreted outside of cells, and which circulates in the peripheral blood, is called circulating microRNA. Systemic lupus erythematosus (SLE) is a typical autoimmune connective tissue disease and is mainly treated with immunosuppressive drugs. Therapeutic apheresis is often used to eliminate autoantibodies and cytokines. We have previously shown that circulating miRNAs in the blood of patients with SLE can be separated and removed from the blood using a plasma separation membrane. In the present study, we further separated circulating miRNA from three SLE patient's blood plasma by passing it through a plasma adsorption membrane, and then measured changes in miRNA levels using miRNAs microarray chip. Although the levels of many miRNAs were unaffected after passage through the plasma adsorption membrane, expression of some miRNAs, including miR-1246, miR-4732-5p, and miR-6088 are declined.

MicroRNAs (miRNAs), which are important inhibitors of mRNA translation, participate in differentiation, migration, cell proliferation, and cell death. The pathology of miRNAs results in alterations in protein expression. Recently, miRNAs circulating in peripheral blood have been shown to control the synthesis and translation of proteins at distal sites after intake into local cells. A number of studies are currently being conducted to investigate how to use miRNAs in disease treatment, but no studies have attempted to alleviate disease by directly eliminating miRNAs from blood. Therefore, we examined whether the removal or reduction of circulating miRNAs with apheresis improved pathologies caused by miRNAs. After approval of the study by our medical school's ethics committee, we collected blood and separated plasma samples from three patients with systemic lupus erythematosus who were undergoing plasmapheresis at our hospital. Peripheral blood was collected before and after it was passed through a primary membrane, centrifuged, and used to extract circulating miRNAs. A comprehensive expression analysis was then performed with a miRNA array chip. The levels of expression of a large number of circulating miRNAs were measured in the plasma samples separated by the primary membranes from all 3 patients with systemic lupus erythematosus. We present the first report that circulating miRNAs in peripheral blood can be separated and possibly directly removed using membrane separation apheresis.