Psoriatic Arthritis Patient Sample Collection

Blood and synovial fluid samples were collected with written informed patient consent from PsA patients undergoing intra-articular aspiration at Oxford University Hospitals. The study was performed in accordance with protocols approved by the Oxford Research Ethics committee (Ethics reference number 06/Q1606/139). Synovial tissue was obtained from knee joints of PsA patients prior to commencement of any immunomodulatory therapy, including systemic corticosteroids by a minimally invasive, ultrasound-guided technique with written informed consent^{30 (link)}. Protocols for these procedures were approved by relevant research ethics committees (reference number 12/NE/0251 Newcastle and West Midlands Black Country Research Ethics committee 07/H1203/57 (Birmingham)). Upon collection of biopsies, they were immediately cryopreserved in cryopreservation media Cryostor CS10 (Sigma—MERCK)^{31 (link)}. Demographics for all patients enrolled in this study are listed in Supplementary Table 1.