Activation of natural killer T cells by alpha-galactosylceramide treatment prevents the onset and recurrence of autoimmune Type 1 diabetes.

Type 1 diabetes (T1D) in non-obese diabetic (NOD) mice may be favored by immune dysregulation leading to the hyporesponsiveness of regulatory T cells and activation of effector T-helper type 1 (Th1) cells. The immunoregulatory activity of natural killer T (NKT) cells is well documented, and both interleukin (IL)-4 and IL-10 secreted by NKT cells have important roles in mediating this activity. NKT cells are less frequent and display deficient IL-4 responses in both NOD mice and individuals at risk for T1D (ref. 8), and this deficiency may lead to T1D (refs. 1,6-9). Thus, given that NKT cells respond to the alpha-galactosylceramide (alpha-GalCer) glycolipid in a CD1d-restricted manner by secretion of Th2 cytokines, we reasoned that activation of NKT cells by alpha-GalCer might prevent the onset and/or recurrence of T1D. Here we show that alpha-GalCer treatment, even when initiated after the onset of insulitis, protects female NOD mice from T1D and prolongs the survival of pancreatic islets transplanted into newly diabetic NOD mice. In addition, when administered after the onset of insulitis, alpha-GalCer and IL-7 displayed synergistic effects, possibly via the ability of IL-7 to render NKT cells fully responsive to alpha-GalCer. Protection from T1D by alpha-GalCer was associated with the suppression of both T- and B-cell autoimmunity to islet beta cells and with a polarized Th2-like response in spleen and pancreas of these mice. These findings raise the possibility that alpha-GalCer treatment might be used therapeutically to prevent the onset and recurrence of human T1D.

Anti-GBM disease: predictive value of clinical, histological and serological data.

Twenty-nine patients with anti-glomerular basement membrane (GBM) disease, defined by circulating anti-GBM antibodies and/or linear deposits of immunoglobulin G along GBM, were studied retrospectively to identify prognostic indicators of renal outcome and pulmonary involvement. Patients consisted of 18 males and 11 females aged 6 to 76 years (mean 35.2 +/- 20.2). Goodpasture syndrome developed in 14, disease was confined to renal manifestations in 14 and isolated pulmonary involvement was present in a single case. Pulmonary disease was significantly associated with current smoking (p < 0.01). Among the 29 patients, end-stage renal failure requiring dialysis was initially observed in 16 (55%). Ten of them had anti-GBM glomerulonephritis (GN) and 4 presented with Goodpasture syndrome; the two other patients died very soon after the beginning of the disease. The 17 patients with an unfavourable renal evolution (group 1) and the 12 patients with favourable evolution or chronic renal failure (group 2) were compared. No significant difference was noted between the two groups concerning the age at onset of the disease, sex, cigarette smoking or pulmonary involvement. Conversely, creatininemia over 600 mumol/l, oligoanuria, absence of normal glomeruli, a high percentage of circumferential crescents, circulating anti-GBM antibodies detected by immunofluorescence, and a high level of circulating anti-GBM antibodies evaluated by ELISA were features which indicate an unfavourable renal course (p < 0.01).

IL-7 up-regulates IL-4 production by splenic NK1.1+ and NK1.1- MHC class I-like/CD1-dependent CD4+ T cells.

NK T cells are an unusual subset of T lymphocytes. They express NK1. 1 Ag, are CD1 restricted, and highly skewed toward Vbeta8 for their TCR usage. They express the unique potential to produce large amounts of IL-4 and IFN-gamma immediately upon TCR cross-linking. We previously showed in the thymus that the NK T subset requires IL-7 for its functional maturation. In this study, we analyzed whether IL-7 was capable of regulating the production of IL-4 and IFN-gamma by the discrete NK T subset of CD4+ cells in the periphery. Two hours after injection of IL-7 into mice, or after a 4-h exposure to IL-7 in vitro, IL-4 production by CD4+ cells in response to anti-TCR-alphabeta is markedly increased. In contrast, IFN-gamma production remains essentially unchanged. In beta2-microglobulin- and CD1-deficient mice, which lack NK T cells, IL-7 treatment does not reestablish normal levels of IL-4 by CD4+ T cells. Moreover, we observe that in wild-type mice, the memory phenotype (CD62L-CD44+) CD4+ T cells responsible for IL-4 production are not only NK1.1+ cells, but also NK1.1- cells. This NK1.1-IL-4-producing subset shares three important characteristics with NK T cells: 1) Vbeta8 skewing; 2) CD1 restriction as demonstrated by their absence in CD1-deficient mice and relative overexpression in MHC II null mice; 3) sensitivity to IL-7 in terms of IL-4 production. In conclusion, the present study provides evidence that CD4+MHC class I-like-dependent T cell populations include not only NK1.1+ cells, but also NK1.1- cells, and that these two subsets are biased toward IL-4 production by IL-7.

Fas/Fas ligand interactions promote activation-induced cell death of NK T lymphocytes.

NKT cells are a versatile population whose immunoregulatory functions are modulated by their microenvironment. We demonstrate herein that in addition to their IFN-gamma production, NKT lymphocytes stimulated with IL-12 plus IL-18 in vitro underwent activation in terms of CD69 expression, blast transformation, and proliferation. Yet they were unable to survive in culture because, once activated, they were rapidly eliminated by apoptosis, even in the presence of their survival factor IL-7. This process was preceded by up-regulation of Fas (CD95) and Fas ligand expression in response to IL-12 plus IL-18 and was blocked by zVAD, a large spectrum caspase inhibitor, as well as by anti-Fas ligand mAb, suggesting the involvement of the Fas pathway. In accordance with this idea, NKT cells from Fas-deficient C57BL/6-lpr/lpr mice did not die in these conditions, although they shared the same features of cell activation as their wild-type counterpart. Activation-induced cell death occurred also after TCR engagement in vivo, since NKT cells became apoptotic after injection of their cognate ligand, alpha-galactosylceramide, in wild-type, but not in Fas-deficient, mice. Taken together, our data provide the first evidence for a new Fas-dependent mechanism allowing the elimination of TCR-dependent or -independent activated NKT cells, which are potentially dangerous to the organism.

NKT lymphocyte ontogeny and function are impaired in low antibody-producer Biozzi mice: gene mapping in the interval-specific congenic strains raised for immunomodulatory genes.

NKT cells are CD4(+) or CD4(-)CD8(-) CD1d-restricted lymphocytes, characterized by the property to rapidly produce IL-4 and IFN-gamma in response to TCR ligation. This IL-4 burst is lacking in autoimmunity-prone SJL and NOD strains of mice, which suggests an immunoregulatory role for NKT cells. The NKT cell status was thus investigated in the genetically selected high (H) and low (L) antibody-producer mice. The results show that (i) the frequency of cells expressing the NKT cell markers is 3- to 4-fold lower in thymus and spleen from L than H mice, (ii) L mice spleen cells did not produce IL-4 following injection of anti-TCR alpha beta antibody, and (iii) L mice thymus and spleen cells failed to produce IL-4 after in vitro stimulation by anti-TCR alpha beta antibody or alpha-galactosylceramide, a newly described NKT cell ligand. These parameters were investigated in six interval-specific congenic strains raised for the quantitative trait loci which contain the immunomodulatory genes responsible for the high/low antibody production phenotypes. IL-4 production recovery occurred only in the congenic strain in which the H origin chromosome 4 segment was introgressed on the L background. This finding was not due to increased NKT cell frequency but appeared dependent of antigen-presenting cells in co-culture experiments. This result strongly suggests the presence of gene(s) modulating NKT function on chromosome 4, close to several genes predisposing to autoimmunity.