Anti-LFA-1 induces CD8 T-cell dependent allograft tolerance and augments suppressor phenotype CD8 cells.

The induction of tolerance to transplanted organs is a major objective in transplantation immunology research. Lymphocyte function-associated antigen-1 (LFA-1) interactions have been identified as a key component of the T-cell activation process that may be interrupted to lead to allograft tolerance. In mice, αLFA-1 mAb is a potent monotherapy that leads to the induction of donor-specific transferable tolerance. By interrogating important adaptive and innate immunity pathways, we demonstrate that the induction of tolerance relies on CD8+T-cells. We further demonstrate that αLFA-1 induced tolerance is associated with CD8+CD28-T-cells with a suppressor phenotype, and that while CD8 cells are present, the effector T-cell response is abrogated. A recent publication has shown that CD8+CD28- cells are not diminished by cyclosporine or rapamycin, therefore CD8+CD28- cells represent a clinically relevant population. To our knowledge, this is the first time that a mechanism for αLFA-1 induced tolerance has been described.

A Preclinical Consortium Approach for Assessing the Efficacy of Combined Anti-CD3 Plus IL-1 Blockade in Reversing New-Onset Autoimmune Diabetes in NOD Mice.

There is an ongoing need to develop strategic combinations of therapeutic agents to prevent type 1 diabetes (T1D) or to preserve islet ß-cell mass in new-onset disease. Although clinical trials using candidate therapeutics are commonly based on preclinical studies, concern is growing regarding the reproducibility as well as the potential clinical translation of reported results using animal models of human disorders. In response, the National Institutes of Health Immune Tolerance Network and JDRF established a multicenter consortium of academic institutions designed to assess the efficacy and intergroup reproducibility of clinically applicable immunotherapies for reversing new-onset disease in the NOD mouse model of T1D. Predicated on prior studies, this consortium conducted coordinated, prospective studies, using joint standard operating procedures, fixed criteria for study entry, and common reagents, to optimize combined anti-CD3 treatment plus interleukin-1 (IL-1) blockade to reverse new-onset disease in NOD mice. We did not find that IL-1 blockade with anti-IL-1ß monoclonal antibody or IL-1trap provided additional benefit for reversing new-onset disease compared with anti-CD3 treatment alone. These results demonstrate the value of larger, multicenter preclinical studies for vetting and prioritizing therapeutics for future clinical use.

Transient B-cell depletion with anti-CD20 in combination with proinsulin DNA vaccine or oral insulin: immunologic effects and efficacy in NOD mice.

A recent type 1 diabetes (T1D) clinical trial of rituximab (a B cell-depleting anti-CD20 antibody) achieved some therapeutic benefit in preserving C-peptide for a period of approximately nine months in patients with recently diagnosed diabetes. Our previous data in the NOD mouse demonstrated that co-administration of antigen (insulin) with anti-CD3 antibody (a T cell-directed immunomodulator) offers better protection than either entity alone, indicating that novel combination therapies that include a T1D-related autoantigen are possible. To accelerate the identification and development of novel combination therapies that can be advanced into the clinic, we have evaluated the combination of a mouse anti-CD20 antibody with either oral insulin or a proinsulin-expressing DNA vaccine. Anti-CD20 alone, given once or on 4 consecutive days, produced transient B cell depletion but did not prevent or reverse T1D in the NOD mouse. Oral insulin alone (twice weekly for 6 weeks) was also ineffective, while proinsulin DNA (weekly for up to 12 weeks) showed a trend toward modest efficacy. Combination of anti-CD20 with oral insulin was ineffective in reversing diabetes in NOD mice whose glycemia was controlled with SC insulin pellets; these experiments were performed in three independent labs. Combination of anti-CD20 with proinsulin DNA was also ineffective in diabetes reversal, but did show modest efficacy in diabetes prevention (p = 0.04). In the prevention studies, anti-CD20 plus proinsulin resulted in modest increases in Tregs in pancreatic lymph nodes and elevated levels of proinsulin-specific CD4+ T-cells that produced IL-4. Thus, combination therapy with anti-CD20 and either oral insulin or proinsulin does not protect hyperglycemic NOD mice, but the combination with proinsulin offers limited efficacy in T1D prevention, potentially by augmentation of proinsulin-specific IL-4 production.

MHC-mismatched islet allografts are vulnerable to autoimmune recognition in vivo.

When transplanted into type 1a diabetic recipients, islet allografts are subject both to conventional allograft immunity and, presumably, to recurrent autoimmune (islet-specific) pathogenesis. Importantly, CD4 T cells play a central role both in islet allograft rejection and in autoimmune disease recurrence leading to the destruction of syngeneic islet transplants in diabetic NOD mice. However, it is unclear how NOD host MHC class II (I-A(g7))-restricted, autoreactive CD4 T cells may also contribute to the recognition of allogeneic islet grafts that express disparate MHC class II molecules. We hypothesized that islet-specific CD4 T cells can target MHC-mismatched islet allografts for destruction via the "indirect" (host APC-dependent) pathway of Ag recognition. To test this hypothesis, we determined whether NOD-derived, islet-specific CD4 T cells (BDC-2.5 TCR transgenic cells) could damage MHC-mismatched islets in vivo independent of conventional allograft immunity. Results demonstrate that BDC-2.5 CD4 T cells can vigorously destroy MHC class II-disparate islet allografts established in NOD.scid recipients. Tissue injury is tissue-specific in that BDC-2.5 T cells destroy donor-type islet, but not thyroid allografts established in the same NOD.scid recipient. Furthermore, BDC-2.5 CD4 T cells acutely destroy MHC class II-deficient islet allografts in vivo, indicating that autoimmune pathogenesis can be completely independent of donor MHC class II expression. Taken together, these findings indicate that MHC-mismatched islet allografts can be vulnerable to autoimmune pathogenesis triggered by autoreactive CD4 T cells, presumably through indirect autoantigen recognition in vivo.