Elevated levels of TRAIL in systemic lupus erythematosus are associated to the presence of anti-SSA/SSB antibodies

The objective of this study was to determine potential relationship between the levels of serum TNF-related apoptosis inducing ligand (TRAIL) and osteoprotegerin (OPG) and clinical markers in systemic lupus erythematosus (SLE) patients. Forty SLE patients with inactive disease were enrolled in this study. For comparison, 20 Sjogren's syndrome (SS) patients and 30 normal controls were also analysed. Serum levels of TRAIL and OPG were determined by ELISA. Serum TRAIL and OPG concentrations in SLE patients were significantly (P < 0.05) higher than those in healthy volunteers. Of note, serum TRAIL but not OPG was significantly (P < 0.05) higher in the SLE patient subset characterized by the presence of anti-SSA/SSB antibodies. The relationship between high levels of TRAIL and SSA/SSB antibodies was further supported by the analysis of SS patients characterized by SSA/SSB antibodies positivity, in which TRAIL levels resulted comparable to the subgroup of anti-SSA/SSB positive SLE patients. The presence of SSA/SSB antibodies, targeting a specific subset of SLE and SS patients, is related to increased serum levels of TRAIL but not of OPG.