Different subsets of natural killer T cells may vary in their roles in health and disease.

Natural killer T cells (NKT) can regulate innate and adaptive immune responses. Type I and type II NKT cell subsets recognize different lipid antigens presented by CD1d, an MHC class-I-like molecule. Most type I NKT cells express a semi-invariant T-cell receptor (TCR), but a major subset of type II NKT cells reactive to a self antigen sulphatide use an oligoclonal TCR.

NKT cells stimulated by long fatty acyl chain sulfatides significantly reduce the incidence of type 1 diabetes in nonobese diabetic mice [corrected].

Sulfatide-reactive type II NKT cells have been shown to regulate autoimmunity and anti-tumor immunity. Although, two major isoforms of sulfatide, C16:0 and C24:0, are enriched in the pancreas, their relative role in autoimmune diabetes is not known. Here, we report that sulfatide/CD1d-tetramer(+) cells accumulate in the draining pancreatic lymph nodes, and that treatment of NOD mice with sulfatide or C24:0 was more efficient than C16:0 in stimulating the NKT cell-mediated transfer of a delay in onset from T1D into NOD.

Structure-guided design of an invariant natural killer T cell agonist for optimum protection from type 1 diabetes in non-obese diabetic mice.

Because invariant natural killer T (iNK T) cells link innate and adaptive immunity, the structure-dependent design of iNK T cell agonists may have therapeutic value as vaccines for many indications, including autoimmune disease. Previously, we showed that treatment of non-obese diabetic (NOD) mice with the iNK T cell activating prototypic glycolipid α-galactosylceramide (α-GalCer) protects them from type 1 diabetes (T1D). However, α-GalCer is a strong agonist that can hyperactivate iNK T cells, elicit several side effects and has shown only limited success in clinical trials.

Stimulation of a shorter duration in the state of anergy by an invariant natural killer T cell agonist enhances its efficiency of protection from type 1 diabetes.

We have reported previously that treatment of non-obese diabetic (NOD) mice with the invariant natural killer T (iNK T) cell agonist α-galactosylceramide C26:0 (α-GalCer) or its T helper type 2 (Th2)-biasing derivative α-GalCer C20:2 (C20:2) protects against type 1 diabetes (T1D), with C20:2 yielding greater protection. After an initial response to α-GalCer, iNK T cells become anergic upon restimulation. While such anergic iNK T cells can induce tolerogenic dendritic cells (DCs) that mediate protection from T1D, chronic administration of α-GalCer also results in long-lasting anergy accompanied by significantly reduced iNK T cell frequencies, which raises concerns about its long-term therapeutic use.

Engagement of glycosylphosphatidylinositol-anchored proteins results in enhanced mouse and human invariant natural killer T cell responses.

Invariant natural killer T (iNKT) cells are a small subset of lymphocytes that recognize glycolipid antigens in the context of CD1d and consequently produce large quantities of pro-inflammatory and/or anti-inflammatory cytokines. Several transmembrane glycoproteins have been implicated in the co-stimulation of iNKT cell responses. However, whether glycosylphosphatidylinositol (GPI)-anchored proteins can function in this capacity is not known.

Neutralization of interleukin-16 protects nonobese diabetic mice from autoimmune type 1 diabetes by a CCL4-dependent mechanism.

Objective: The progressive infiltration of pancreatic islets by lymphocytes is mandatory for development of autoimmune type 1 diabetes. This inflammatory process is mediated by several mediators that are potential therapeutic targets to arrest development of type 1 diabetes. In this study, we investigate the role of one of these mediators, interleukin-16 (IL-16), in the pathogenesis of type 1 diabetes in NOD mice.

An alpha-galactosylceramide C20:2 N-acyl variant enhances anti-inflammatory and regulatory T cell-independent responses that prevent type 1 diabetes.

Protection from type 1 diabetes (T1D), a T helper type 1 (Th1)-mediated disease, is achievable in non-obese diabetic (NOD) mice by treatment with alpha-galactosylceramide (alpha-GalCer) glycolipids that stimulate CD1d-restricted invariant natural killer T (iNK T) cells. While we have reported previously that the C20:2 N-acyl variant of alpha-GalCer elicits a Th2-biased cytokine response and protects NOD mice from T1D more effectively than a form of alpha-GalCer that induces mixed Th1 and Th2 responses, it remained to determine whether this protection is accompanied by heightened anti-inflammatory responses. We show that treatment of NOD mice with C20:2 diminished the activation of 'inflammatory' interleukin (IL)-12 producing CD11c(high)CD8+ myeloid dendritic cells (mDCs) and augmented the function of 'tolerogenic' DCs more effectively than treatment with the prototypical iNKT cell activator KRN7000 (alpha-GalCer C26:0) that induces Th1- and Th2-type responses.

Intravenous transfusion of BCR-activated B cells protects NOD mice from type 1 diabetes in an IL-10-dependent manner.

Although B cells play a pathogenic role in the initiation of type 1 diabetes (T1D) in NOD mice, it is not known whether activated B cells can maintain tolerance and transfer protection from T1D. In this study, we demonstrate that i.v.

Decreased renal ischemia-reperfusion injury by IL-16 inactivation.

T-cell-mediated renal injury is a major cause of kidney transplant rejection and renal failure; hence, understanding T-cell migration within the kidney is important for preventing renal injury. Interleukin (IL)-16 is a T-cell chemoattractant produced by leukocytes. Here we measured IL-16 expression in the kidney and its role in renal ischemia-reperfusion injury induced by different conditions in several strains of mice.

CCL4 protects from type 1 diabetes by altering islet beta-cell-targeted inflammatory responses.

We previously reported that interleukin (IL)-4 treatment of nonobese diabetic (NOD) mice elevates intrapancreatic CCL4 expression and protects from type 1 diabetes. Here, we show that antibody neutralization of CCL4 abrogates the ability of T-cells from IL-4-treated NOD mice to transfer protection against type 1 diabetes. Intradermal delivery of CCL4 via a plasmid vector stabilized by incorporation of the Epstein-Barr virus EBNA1/oriP episomal maintenance replicon (pHERO8100-CCL4) to NOD mice beginning at later stages of disease progression protects against type 1 diabetes.

Characterization of PAF-AH Ib1 in NOD mice: PAF-AH may not be a candidate gene of the diabetes susceptibility Idd4.1 locus.

We recently mapped Idd4 to a 5.2 cM interval on chromosome 11 with two subloci, Idd4.1 and Idd4.

Protection from type 1 diabetes by invariant NK T cells requires the activity of CD4+CD25+ regulatory T cells.

Invariant NK T (iNKT) cells regulate immune responses, express NK cell markers and an invariant TCR, and recognize lipid Ags in a CD1d-restricted manner. Previously, we reported that activation of iNKT cells by alpha-galactosylceramide (alpha-GalCer) protects against type 1 diabetes (T1D) in NOD mice via an IL-4-dependent mechanism. To further investigate how iNKT cells protect from T1D, we analyzed whether iNKT cells require the presence of another subset(s) of regulatory T cells (Treg), such as CD4+ CD25+ Treg, for this protection.

The autoimmune regulator (Aire) controls iNKT cell development and maturation.

The mechanism underlying the autoimmune polyglandular syndrome type-1 (APS1) has been attributed to defective T-cell negative selection resulting from reduced expression and presentation of autoantigens in thymic medullary epithelial cells (MECs). It has also been postulated that Aire is involved in development of regulatory T cells, although supporting evidence is lacking. Here we show that expression of Aire in MECs is required for development of iNKT cells, suggesting a role for iNKT cells in APS1.

A defect in lineage fate decision during fetal thymic invariant NKT cell development may regulate susceptibility to type 1 diabetes.

A numerical and functional deficiency in invariant NKT (iNKT) cells detectable by 3 wk of age in the thymus and spleen mediates the pathogenesis of type 1 diabetes in NOD mice, but the stage of T cell development at which this deficiency first occurs is unknown. We report in this study that this deficiency develops after the CD4(+)CD8(+) double-positive stage of thymic T cell development and is due to a lineage-specific depletion of CD4(-)CD8(-) double-negative alphabeta T cells and iNKT cells from the thymus between embryonic day 18 and day 1 after birth. Thus, an inheritable defect in a lineage fate decision that elicits a deficiency in fetal thymic iNKT cell development may predispose to susceptibility to type 1 diabetes.

Role of regulatory invariant CD1d-restricted natural killer T-cells in protection against type 1 diabetes.

Invariant CD1d-restricted natural killer T (iNKT) cells function during innate and adaptive immune responses. A functional and numerical deficiency of iNKT cells is well documented in both nonobese diabetic (NOD) mice and humans with autoimmune type 1 diabetes (T1D). Restoring the numerical and/or functional deficiency of iNKT cells in NOD mice by either treatment with alpha-galactosylceramide, transgenic induction of Valpha14-Jalpha18 expression, or transgenic expression of CD1d in NOD islets under the control of the human insulin promoter confers protection from T1D in these mice.

Dysregulated B7-1 and B7-2 expression on nonobese diabetic mouse B cells is associated with increased T cell costimulation and the development of insulitis.

Little is known about the pathogenic role of B cell dysfunction in T cell-mediated autoimmune disease. We previously reported that B cell hyper-responsiveness, resistance to apoptosis, and accumulation in islets occur during the onset of insulitis, but not in type 1 diabetes (T1D), in NOD mice. In this study we extended these studies to further determine how islet-infiltrated B cells contribute to this inflammatory insulitis.

Perturbed homeostasis of peripheral T cells elicits decreased susceptibility to anti-CD3-induced apoptosis in prediabetic nonobese diabetic mice.

Activation-induced cell death (AICD) plays a key role in the homeostasis of the immune system. Autoreactive T cells are eliminated through AICD both from the thymus and periphery. In this study, we show that NOD peripheral T cells, especially CD8(+) T cells, display a decreased susceptibility to anti-CD3-induced AICD in vivo compared with T cells from diabetes-resistant B6, nonobese diabetes-resistant, and NOD.

Hyperresponsiveness, resistance to B-cell receptor-dependent activation-induced cell death, and accumulation of hyperactivated B-cells in islets is associated with the onset of insulitis but not type 1 diabetes.

B-cells proliferate after B-cell receptor (BCR) stimulation and are deleted by activation-induced cell death (AICD) during negative selection. We report that B-cells from type 1 diabetes-susceptible NOD and type 1 diabetes-resistant but insulitis-prone congenic NOD.B6Idd4B and NOR mice, relative to B-cells from nonautoimmune disease-prone C57BL/6 and BALB/c mice, display a hyperproliferative response to BCR stimulation and lower activation threshold in the absence or presence of interleukin 4 (IL-4).

Interleukin-4 but not interleukin-10 protects against spontaneous and recurrent type 1 diabetes by activated CD1d-restricted invariant natural killer T-cells.

In nonobese diabetic (NOD) mice, a deficiency in the number and function of invariant natural killer T-cells (iNKT cells) contributes to the onset of type 1 diabetes. The activation of CD1d-restricted iNKT cells by alpha-galactosylceramide (alpha-GalCer) corrects these deficiencies and protects against spontaneous and recurrent type 1 diabetes. Although interleukin (IL)-4 and IL-10 have been implicated in alpha-GalCer-induced protection from type 1 diabetes, a precise role for these cytokines in iNKT cell regulation of susceptibility to type 1 diabetes has not been identified.

Insulin-like growth factor (IGF)-I/IGF-binding protein-3 complex: therapeutic efficacy and mechanism of protection against type 1 diabetes.

IGF-I regulates islet beta-cell growth, survival, and metabolism and protects against type 1 diabetes (T1D). However, the therapeutic efficacy of free IGF-I may be limited by its biological half-life in vivo. We investigated whether prolongation of its half-life as an IGF-I/IGF binding protein (IGFBP)-3 complex affords increased protection against T1D and whether this occurs by influencing T cell function and/or islet beta-cell growth and survival.

CD1d-restricted NKT regulatory cells: functional genomic analyses provide new insights into the mechanisms of protection against Type 1 diabetes.

Deficiencies in NKT cell number and function mediate the development of Type 1 diabetes (TID). NKT cell activation with the CD1d ligand alpha-galactosylceramide (alpha-GalCer) corrects these deficiencies and prevents the onset and recurrence of T1D in NOD mice. To investigate how alpha-GalCer accomplishes this, we conducted three sets of studies.

Blockade of tumor necrosis factor-related apoptosis-inducing ligand exacerbates type 1 diabetes in NOD mice.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is expressed in different tissues and cells, including pancreas and lymphocytes, and can induce apoptosis in various tumor cells but not in most normal cells. The specific roles of TRAIL in health and disease remain unclear. Here we show by cDNA array analyses that TRAIL gene expression is upregulated in pancreatic islets during the development of autoimmune type 1 diabetes in nonobese diabetic (NOD) mice and in Min6 islet beta-cells activated by TNF-alpha + interferon-gamma.