Baert, Laurie

Abstract Description tolerance is the “holy grail” in the fields of transplantation medicine and the treatment of autoimmune diseases. We previously reported that TIGIT+ B cells can efficiently control inflammatory responses while promoting regulatory T cell response via the ligation of CD155 expressed on both T cells and dendritic cells (DCs). Recent studies have also demonstrated that lack of TIGIT expression in B cells can lead to inflammation in the central nervous system in both humans and mice. These findings prompted us to explore whether TIGIT+ B cell therapy model could be developed for the treatment of inflammatory diseases. In this study, we report that TIGIT+ B cells can be generated with replication-incompetent recombinant Adv5 vectors designed to target CD21 on B cells. Those TIGIT+ B cells generated with our novel Adv5 vectors can efficiently control inflammatory T cell responses in vitro by directly acting on T cells and by regulating inflammatory function of DCs. The preclinical efficacy of TIGIT+ B cell therapy model and its underlying mechanisms of action are also investigated using an experimental autoimmune encephalomyelitis model. Data from this study support the clinical development of this novel TIGIT+ B cell therapy model for the treatment of inflammatory diseases. Funding Sources Mayo Clinic Cancer Center Topic Categories Therapeutic Approaches to Autoimmunity (THER)

Pathophysiologic function of B cells in graft rejection has been well recognized in transplantation. B cells promote alloantigen-specific T-cell response and secrete antibodies that can cause antibody-mediated graft failures and rejections. Therefore, strategies targeting B cells, for example, B-cell depletion, have been used for the prevention of both acute and chronic rejections. Interestingly, however, recent mounting evidence indicates that subsets of B cells yet to be further identified can display potent immune regulatory functions, and they contribute to transplantation tolerance and operational tolerance in both experimental and clinical settings, respectively. In this review, we integrate currently available information on B-cell subsets, including T-cell Ig domain and mucin domain 1-positive transitional and T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif domain-positive memory B cells, displaying immune regulatory functions, with a focus on transplantation tolerance, by analyzing their mechanisms of action. In addition, we will discuss potential T-cell Ig domain and mucin domain 1-positive and T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif domain-positive B cell–based strategies for the enhancement of operational tolerance in transplantation patients.