Although the autoimmune destruction of pancreatic β-cells underlying type 1 diabetes (T1D) development is ultimately mediated by T cells in NOD mice and also likely in humans, B cells play an additional key pathogenic role. It appears that the expression of plasma membrane–bound Ig molecules that efficiently capture β-cell antigens allows autoreactive B cells that bypass normal tolerance induction processes to be the subset of antigen-presenting cells most efficiently activating diabetogenic T cells. NOD mice transgenically expressing Ig molecules recognizing antigens that are (insulin) or are not (hen egg lysozyme [HEL]) expressed by β-cells have proven useful in dissecting the developmental basis of diabetogenic B cells. However, these transgenic Ig specificities were originally selected for their ability to recognize insulin or HEL as foreign, rather than autoantigens. Thus, we generated and characterized NOD mice transgenically expressing an Ig molecule representative of a large proportion of naturally occurring islet-infiltrating B cells in NOD mice recognizing the neuronal antigen peripherin. Transgenic peripherin-autoreactive B cells infiltrate NOD pancreatic islets, acquire an activated proliferative phenotype, and potently support accelerated T1D development. These results support the concept of neuronal autoimmunity as a pathogenic feature of T1D, and targeting such responses could ultimately provide an effective disease intervention approach.

Autoreactive B lymphocytes play a key role as APCs in diaebetogenesis. However, it remains unclear whether B-cell tolerance is compromised in NOD mice. Here, we describe a new B lymphocyte transgenic NOD mouse model, the 116C-NOD mouse, where the transgenes derive from an islet-infiltrating B lymphocyte of a (8.3-NODxNOR) F1 mouse. The 116C-NOD mouse produces clonal B lymphocytes with pancreatic islet beta cell specificity. The incidence of T1D in 116C-NOD mice is decreased in both genders when compared with NOD mice. Moreover, several immune selection mechanisms (including clonal deletion and anergy) acting on the development, phenotype, and function of autoreactive B lymphocytes during T1D development have been identified in the 116C-NOD mouse. Surprisingly, a more accurate analysis revealed that, despite their anergic phenotype, 116C B cells express some costimulatory molecules after activation, and induce a T-cell shift toward a Th17 phenotype. Furthermore, this shift on T lymphocytes seems to occur not only when both T and B cells contact, but also when helper T (Th) lineage is established. The 116C-NOD mouse model could be useful to elucidate the mechanisms involved in the generation of Th-cell lineages.Keywords: B lymphocyte r Immune tolerance r NOD mouse r Th17 r Transgenic r Type 1 diabetes Additional supporting information may be found in the online version of this article at the publisher's web-site Correspondence: Dr. Joan Verdaguer e-mail: joan.verdaguer@mex.udl.cat * These authors contributed equally to this work.C 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu 594Jorge Carrascal et al. Eur. J. Immunol. 2016. 46: 593-608 Introduction Type 1 diabetes (T1D) is an autoimmune disease characterized by selective destruction of pancreatic beta cells [1]. In both humans and mice, the disease begins with insulitis, which consists of a mononuclear infiltrate that progressively destroys islet beta cells and eventually results in diabetes onset. Although T lymphocytes are the major effectors of beta cell damage, over the last decades it has become clear that B lymphocytes also play an important role in the pathogenesis of T1D. In this regard, NOD.IgM null or wild-type NOD mice depleted of this cell population do not develop T1D and/or show a delay in the age of disease onset [2][3][4]. Although the mechanisms by which B lymphocytes contribute to diabetes remain poorly understood, it has been proposed that they act as APCs, capturing beta cell autoantigens via cell surface autoreactive immunoglobulins and presenting them to autoreactive T lymphocytes in regional lymph nodes [5][6][7]. Moreover, B lymphocytes migrate to pancreatic islets during the development of T1D [8], thus suggesting a key function in the progression of the disease in situ.To elucidate the antigen specificity of islet-infiltrating B lymphocytes during disease progression, hybridoma cell lines of infiltrating B lymphocytes from NOD mice and other related strains developing insulitis were generated [9]. Only a small per...

Previous studies indicate that B-lymphocytes play a key role activating diabetogenic T-lymphocytes during the development of autoimmune diabetes. Recently, two transgenic NOD mouse models were generated: the NOD- PerIg and the 116C-NOD mice. In NOD- PerIg mice, B-lymphocytes acquire an activated proliferative phenotype and support accelerated autoimmune diabetes development. In contrast, in 116C-NOD mice, B-lymphocytes display an anergic-like phenotype delaying autoimmune diabetes onset and decreasing disease incidence. The present study further evaluates the T- and B-lymphocyte phenotype in both models. In islet-infiltrating B-lymphocytes (IIBLs) from 116C-NOD mice, the expression of H2-K d and H2-A g7 is decreased, whereas that of BAFF, BAFF-R, and TACI is increased. In contrast, IIBLs from NOD- PerIg show an increase in CD86 and FAS expression. In addition, islet-infiltrating T-lymphocytes (IITLs) from NOD- PerIg mice exhibit an increase in PD-1 expression. Moreover, proliferation assays indicate a high capacity of B-lymphocytes from NOD- PerIg mice to secrete high amounts of cytokines and induce T-lymphocyte activation compared to 116C B-lymphocytes. This functional variability between 116C and PerIg B-lymphocytes ultimately results in differences in the ability to shape T-lymphocyte phenotype. These results support the role of B-lymphocytes as key regulators of T-lymphocytes in autoimmune diabetes and provide essential information on the phenotypic characteristics of the T- and B-lymphocytes involved in the autoimmune response in autoimmune diabetes.