The Expression Of A Proliferation-inducing Ligand In Patients With Systemic Lupus Erythematosus, Rheumatic Arthritis And The Functional Study Of Its Receptor Fusion Protein

Objective: To study the expression and clinical significance of A proliferation-inducing ligand (APRIL)and the relationship between APRIL and B cell activating factor belonging to the TNF family activating factor (BAFF) expressed in patients with systemic lupus erythematosus (SLE)and rheumatic arthritis (RA) and to find a new approach to the treatment of SLE and RA with transmembrane activator and CAML-interactor (TACI)-BAFF receptor (BR3) receptor's fusion protein. Method: Using real-time fluorescent quantitative polymerase chain reaction and ELISA methods was used to detect the expression of APRIL/BAFF mRNA and protein in patients and in normal control. We detected the levels of serum immunolobulins(IgG, IgA and IgM) and the titres of anti-dsDNA. We have constructed the recombinated eukaryotic expression plasmid-TACI-BR3-pcDNA3.1(+) which was transfected transiently into COS-7, and receptor's fusion protein was expressed by COS-7. The protein purified was used to block the biological function in vitro study. Results: The results showed that the expression of APRIL (gene and protein level) in patients with SLE and RA was higher than that in normal control and was the highest in in no-relieved patients after therapy than that in the others. There was significant relationship not between APRIL and BAFF mRNA expression but between APRIL and BAFF protein expression. In vitro study, recetpor's fusion protein could bind ligands of APRIL and BAFF and block their biological function. Conclusion: APRIL protein and mRNA over-expressed in patients with SLE and RA may be useful factors to auxiliary diagnose and judge prognosis in patients with SLE and RA. Receptor's fusion protein(TACI-BR3) may be used to treat auto-immune diseases by blocking the biological function of APRIL and BAFF.