gms | German Medical Science

Background: G-protein coupled receptors are the largest super family of integral membrane proteins in human. Systemic lupus erythematosus (SLE) is multisystem autoimmune disease characterized by chronic immune activation and the presence of a plethora of autoantibodies. Our hypothesis is that autoantibodies targeting G protein-coupled receptors may have role in the pathogenesis of SLE.

Methods: Sera were obtained from patients with SLE (n=24) and age- and sex-matched healthy controls (n=52). SLE was diagnosed according to the American College of Rheumatology criteria. SLE disease activity was determined by SLEDAI-2K score. Circulating anti-β1/β2 adrenoceptor antibodies, anti-endothelin receptor A (ETAR) antibodies, anti-muscarinic acetylcholine receptor M3 antibodies, anti-C5aR antibodies, anti-CXC chemokine receptor 3 (CXCR3) antibodies and anti-CXC chemokine 4 (CXCR4) antibodies were measured by ELISA.

Results: The concentrations of anti-β1 adrenoceptor antibodies, anti-β2 adrenoceptor antibodies and anti-ETAR antibodies were higher in SLE patients than healthy controls (p<0.05). Further, the concentrations of anti-CXCR3 antibodies, anti-CXCR4 antibodies, anti-C5aR antibodies and anti-M3 receptor antibodies were lower in SLE patients than healthy controls (p<0.05). Anti-CXCR3 antibodies, anti-CXCR4 antibodies, anti-C5aR antibodies and anti-M3 receptor antibodies showed no correlation with SLEDAI-2K, complement 3 and complement 4. However, the concentrations of anti-β1/β2 adrenoceptor antibodies and anti-ETAR antibodies positively correlate with SLEDAI-2K. At the same time, the concentrations of anti-β1/β2 adrenoceptor antibodies and anti-ETAR antibodies negatively correlate with complement 3 and complement 4.

Conclusion: Autoantibodies targeting β1/β2 adrenoceptor and ETAR may have functional roles in the pathogenesis and progression of SLE.