Heat shock protein 70 membrane expression on fibroblast-like synovial cells derived from synovial tissue of patients with rheumatoid and juvenile idiopathic arthritis

Objective: To screen fibroblast-like synovial cells derived from synovial tissue of rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) patients for the membrane expression of the heat shock protein Hsp70. Methods: We performed flow cytometric (fluorescence-activated cell sorting, or FACS) analysis on fibroblast-like synovial cells of 15 RA patients and three JIA patients to investigate Hsp70 membrane expression. Skin fibroblasts derived from the operation wound (n = 4) and peripheral blood mononuclear cells (PBMC) of seven RA and three JIA patients were also tested. Peripheral blood lymphocytes (PBL) and skin fibroblasts of 10 healthy individuals were used as negative controls. Results: A significantly higher percentage of Hsp70 membrane expression was found on fibroblast-like synovial cells derived from arthritis-affected joints in RA patients (mean 47.7%) when compared with autologous skin fibroblasts (mean 9.5%, p<0.001) and control skin fibroblasts (mean 5.6%, p<0.001) or autologous PBL (mean CD45/Hsp70-positive 10.4%, p<0.001) and control PBL (mean CD45/Hsp70-positive 7.7%, p<0.001). A high percentage of Hsp70 membrane expression was also observed on fibroblast-like synovial cells derived from three patients with JIA (mean 35.2%) when compared with autologous PBL (mean CD45/Hsp70-positive 10.4%). Synovial cells derived from non-affected joints in a patient with RA who underwent synovectomy for trauma showed low expression of Hsp70 (10.9%). Conclusion: Fibroblast-like synovial cells derived from patients with severe course of RA and JIA are strongly positive for membrane-expressed Hsp70.