Cytokine clusters as potential diagnostic markers of disease activity and renal involvement in systemic lupus erythematosus

Objective To describe interactions among cytokines and to identify subgroups of systemic lupus erythematosus (SLE) patients based on cytokine levels using principal component analysis and cluster analysis. Methods Levels of 12 cytokines were measured using sensitive multiplex bead assays and associations with SLE features including disease activity and renal involvement were assessed. Results In a group of 203 SLE patients, strong correlations were observed between interleukin (IL)6 and interferon (IFN)gamma levels (r = 0.624), IL17 and IFN gamma levels (r = 0.768), and macrophage inflammatory protein (MIP)1 alpha and MIP1 beta levels (r = 0.675). Cluster analysis revealed two distinct patient groups characterized by high levels of IL8, MIP1 alpha, and MIP1 beta (group 1) or of IL2, IL6, IL10, IL12, IFN gamma, and tumor necrosis factor alpha (group 2). Active disease was more common in group 1 (49/88, 55.7%) than in group 2 (40/115, 34.8%). More patients in group 2 had renal involvement (42/115, 36.5%) than in group 1 (22/88, 25%). Conclusions Assessment of cytokine profiles can identify distinct SLE patient subgroups and aid in understanding clinical heterogeneity and immunological phenotypes.