Microarray analysis of miRNA expression

We analyzed serum miRNA levels (total of 2,565 miRNAs) in patients with PsA at baseline (n = 3), patients with PsA post-granulocyte and monocyte adsorption apheresis (n = 3), and healthy controls (n = 3) using microarray sequencing. Total RNA, including miRNAs, was isolated from sera using the miRNeasy Serum/Plasma kit and miRNeasy Mini kit (QIAGEN Japan, Tokyo, Japan) according to the manufacturers’ instructions. Spike-in controls were used as serum samples. The miRNAs were analyzed using the 3D-Gene miRNA Oligo chip (Toray, Tokyo, Japan).