Decoy Receptor 3 (DcR3) Polymorphisms in Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE)

Although SLE and RA are correlated with genetic predisposing factors such as human leukocyte antigen (HLA) class II, both diseases and other genetic factors might have contributed to the development of dysregulated lymphocyte activation and autoimmunity. Decoy receptor 3 (DcR3)/TR6 is a secreted protein belonging to the tumor necrosis factor (TNF) receptor family. It binds to Fas ligand (FasL), LIGHT, and TL1A that are all TNF family members. It was noted that soluble or solid phase DcR3-Fc co-stimulated proliferation, lymphokine production and cytotoxicity of mouse and human T cells upon T-cell receptor (TCR) ligation. Recently, the investigators found that the serum level of soluble DcR3 was higher in SLE patients than in healthy control subjects (unpublished data). Taken together, the investigators propose that in autoimmune diseases, such as RA and SLE, activated T cells secrete more DcR3 than non-autoimmune controls, which may, in turn, costimulate T cells further and cause dysregulated lymphocyte activation. With the aim to establish the possible correlation between DcR3 genetic polymorphisms, DcR3 expressions, and autoimmune phenotypes, the investigators offer this proposal. They plan to investigate the single nucleotide polymorphisms (SNPs) in the DcR3 gene. The genetic polymorphisms on the DcR3/TR6 gene and circulating DcR3 level will be compared between RA, SLE and non-autoimmune control subjects.