SPDL1 and Arthritis: In conclusion, the findings in this study suggest that intra-articular injection of AAV vectors encoding sPD-L1 results in greater therapeutic benefit on arthritis, and systemic AAV/sPD-L1 is able to block the development of inflammatory arthritis with inhibition of the systemic immune response, underlining the potential of gene therapy with systemic delivery of shPD-L1 via AAV vectors in RA.