Enrichment of tolerogenic B cells for T1D therapy in NOD Mice

A new therapy, called anti-CD20 (Rituximab), has recently been found to lead to clinical improvement in a number of autoimmune diseases. While Rituximab was believed to act by depleting all B cells, it is now realized that anti-CD20 therapy may actually spare certain subsets of cells, namely the so-called marginal zone (MZ) B cells. Indeed, these MZ B cells may be tolerogenic. We recently observed that different B cell activating agents (e.g., LPS and nucleotides called CpG) modulate the behavior of B cells in our gene therapy protocol. Putting these observations together, we propose the hypothesis that LPS and CpG may activate these B cells differentially to modify their antigen presenting capacity leading to tolerogenic or pathogenic consequences. Alternatively, the tolerogenic properties of MZ and follicular (FO) B cells are intrinsic properties of these subsets independent of their mode of activation. We will use these stimuli and anti-CD20 therapy in NOD mouse model of T1D to test this hypothesis. We have developed a gene therapy protocol in which viral expression of target antigens in activated B lymphocytes leads to tolerance in terms of T-cell responses and clinical efficacy in several mouse models of autoimmune diseases, including Type 1 diabetes in NOD mice. In our studies, B cells are activated with a stimulant called LPS, which does not work on human B cells. To move this project forward to apply with human B cells, we examined whether B cells could be activated by different B cell stimuli and if these could be transduced as tolerogenic antigen-presenting cells. We found that B cells activated by CD40 and antibodies to immunoglobulins were tolerogenic but those stimulated by nucleotides call CpG were not tolerogenic. In addition, we know that anti-CD20 therapy can lead to clinical improvement in a number of autoimmune diseases. Recently, it was realized that anti-CD20 therapy may not deplete all B cells, but may spare certain subsets of cells, and that these may be tolerogenic to the immune system. Putting these observations together, we propose the hypothesis that LPS and CpG activate these different types of B cells with decidedly different consequences: tolerance or pathogenicity. We will use these stimuli and anti-CD20 therapy in a mouse model of T1D to test this hypothesis.