Antigen-specific immunotherapies in rheumatic diseases.

The main goal of antigen-specific immunotherapy (ASI) in autoimmune and rheumatic diseases is to reprogramme or remove autoreactive cells and/or induce immune tolerance to self-antigens. Current therapies in these diseases either treat symptoms or slow down disease progression but are not yet curative or preventative - disease-specific treatments are urgently needed. In contrast to the nonspecific treatments in current use that induce generalized immune suppression, which is associated with several adverse effects including increased risk of infections, ASIs target a restricted subset of B cells or T cells, and thus do not compromise systemic immunity and host defence. This Review provides a summary of novel approaches for identifying autoepitopes and detecting and targeting autoreactive cells that might help in the development of ASIs. Promising approaches include the use of tolerizing peptides coupled to MHC constructs and/or nanocompounds, tolerizing dendritic cells and antigen-specific vaccines. Following studies in animal models of rheumatoid arthritis and systemic lupus erythematosus, several of these strategies have now entered clinical trials. However, to use these approaches in humans, several important limitations must first be addressed, such as; selecting the proper immunodominant autoantigen; identifying the optimal timing, dosing and route of administration; finding biomarkers for monitoring the therapy; and optimizing methodology.