Autoreactive Effector/Memory CD4+ and CD8+ T Cells Infiltrating Grafted and Endogenous Islets in Diabetic NOD Mice Exhibit Similar T Cell Receptor Usage

Abstract

Islet transplantation provides a “cure” for type 1 diabetes but is limited in part by recurrent autoimmunity mediated by β cell-specific CD4+ and CD8+ T cells. Insight into the T cell receptor (TCR) repertoire of effector T cells driving recurrent autoimmunity would aid the development of immunotherapies to prevent islet graft rejection. Accordingly, we used a multi-parameter flow cytometry strategy to assess the TCR variable β (Vβ) chain repertoires of T cell subsets involved in autoimmune-mediated rejection of islet grafts in diabetic NOD mouse recipients. Naïve CD4+ and CD8+ T cells exhibited a diverse TCR repertoire, which was similar in all tissues examined in NOD recipients including the pancreas and islet grafts. On the other hand, the effector/memory CD8+ T cell repertoire in the islet graft was dominated by one to four TCR Vβ chains, and specific TCR Vβ chain usage varied from recipient to recipient. Similarly, islet graft- infiltrating effector/memory CD4+ T cells expressed a limited number of prevalent TCR Vβ chains, although generally TCR repertoire diversity was increased compared to effector/memory CD8+ T cells. Strikingly, the majority of NOD recipients showed an increase in TCR Vβ12-bearing effector/memory CD4+ T cells in the islet graft, most of which were proliferating, indicating clonal expansion. Importantly, TCR Vβ usage by effector/memory CD4+ and CD8+ T cells infiltrating the islet graft exhibited greater similarity to the repertoire found in the pancreas as opposed to the draining renal lymph node, pancreatic lymph node, or spleen. Together these results demonstrate that effector/memory CD4+ and CD8+ T cells mediating autoimmune rejection of islet grafts are characterized by restricted TCR Vβ chain usage, and are similar to T cells that drive destruction of the endogenous islets.

Tissue distribution and clonal diversity of the T and B cell repertoire in type 1 diabetes

“…It is widely accepted that diabetogenic T cells are enriched within the pancreatic islets and pLN in NOD mice (8,31). This notion emanates from animal model studies, such as those by Lennon et al, which demonstrated that islet entry and accumulation is an antigen-specific, cell-autonomous event (7).…”

“…A pathogenic role for adaptive immunity is also supported by the development of T1D in recipients of bone marrow transplants from both twin and unrelated T1D donors (4,5). In addition, adoptive transfer experiments in the NOD mouse model support the notion that T cells are both necessary and sufficient for disease development (6) and are retained in pancreatic draining lymph nodes (pLN) prior to and after disease onset (7,8). Hence, there is great interest in monitoring and tracking the T cell repertoire during T1D pathogenesis.…”

Antigen-Encoding Bone Marrow Terminates Islet-Directed Memory CD8+ T-Cell Responses to Alleviate Islet Transplant Rejection

“…BM was flushed with mouse tonicity PBS/2.5% FCS, erythrocytes were lysed (NH 4 Cl/TRIS buffer), and BM was injected intravenously within 3 h of irradiation (300cGy, 137 Cs source). HSPCs for transfer were prepared by highspeed FACS sorting of lin-negative (lin 2ve )/c-kit-positive (c-kit +ve ) cells to typically .95% purity from bulk BM.…”

“…Pathogenic memory T cells are prominent in type 1 diabetes (T1D), where they arise during the early, preclinical phase of disease and are well established by the time of diagnosis (2). In addition to perpetuating disease, islet-specific CD4 + and CD8 + memory T cells are persistent and may remain dormant for extended periods after T1D onset but are rapidly reactivated by islet antigen exposure during islet transplantation and contribute substantially to rejection of transplanted islets (3,4). Thus, immunotherapy for T1D must address memory T cells regardless of disease stage, and this is crucial for success of islet transplantation.…”

Transgenic expression of proinsulin to inactivate insulin-specific CD8+ T-cell responses in autoimmune diabetes

“…In the NOD mouse, immune responses directed toward insulin are required for diabetes development (French et al, 1997;Nakayama et al, 2005). Insulin-reactive Tmem have been identified in the periphery of patients with T1D (Luce et al, 2011) and in the NOD mouse (Chee et al, 2014;Diz et al, 2012). More importantly, insulin-specific CD8 + T cells have been detected in the pLN and islets in human T1D (Coppieters et al, 2012).…”