The role of CD40-CD154 interactions in autoimmunity and the benefit of disrupting this pathway

Many tissue injuries and immune mediated pathologies such as graft allo-rejections were found to involve CD40-CD40 ligand (CD40L, CD154) signaling pathway. The disruption of this pathway in many animal models led to the improvement of graft survival in these models. CD40-CD154 interactions were also shown to play a significant role in the maintenance of autoimmunity, and the production of auto-antibodies in systemic lupus erythematosus (SLE). High-level expression of CD154 has been detected on T cells from patients with active SLE, rheumatoid arthritis (RA) and other autoimmune diseases, indicating that such cells could account for the high-level expression of immune accessory molecules on B cells of patients with active disease. An increased serum level of soluble CD154 was also reported in SLE, RA, and Sjogren's disease in correlation with the relevant autoantibodies and with the clinical disease activity. Anti-CD154 antibody therapy prevents auto-antibody production and renal immune complex deposition in lupus nephritis, indicating that disruption of this pathway could be a beneficial treatment in SLE. However, the etiology of the higher than expected number of thromboembolic events in antiCD154 treated SLE patients should be investigated and preventive measures should be considered.