Accumulating evidence favors a role for proinsulin as a key autoantigen in diabetes. In the mouse, two proinsulin isoforms coexist. Most studies point to proinsulin 2 as the major isoform recognized by T cells in the NOD mouse. We studied mice in which a null proinsulin 2 mutation was transferred from proinsulin 2-deficient 129 mice onto the NOD background along with 16 genetic markers (including I-A g7 MHC molecule) associated with diabetes. Intercross mice from the fourth backcross generation showed that proinsulin 2 -/-mice develop accelerated insulitis and diabetes. The high prevalence of anti-insulin autoantibodies in proinsulin 2 -/-mice indicates that diabetes acceleration relates to altered recognition of proinsulin. The prevalence of anti-glutamic acid decarboxylase autoantibodies and of sialitis is not increased in proinsulin 2 -/-mice. We give evidence that proinsulin 2 expression leads to silencing of T cells specific for an epitope shared by proinsulin 1 and proinsulin 2. In the human, alleles located in the VNTR region flanking the insulin gene control β cell response to glucose and proinsulin expression in the thymus and are key determinants of diabetes susceptibility. Proinsulin 2 -/-NOD mice provide a model to study the role of thymic expression of insulin in susceptibility to diabetes.This article was published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org.

Accumulating evidence favors a role for proinsulin as a key autoantigen in diabetes. In the mouse, two proinsulin isoforms coexist. Most studies point to proinsulin 2 as the major isoform recognized by T cells in the NOD mouse. We studied mice in which a null proinsulin 2 mutation was transferred from proinsulin 2-deficient 129 mice onto the NOD background along with 16 genetic markers (including I-A g7 MHC molecule) associated with diabetes. Intercross mice from the fourth backcross generation showed that proinsulin 2 -/-mice develop accelerated insulitis and diabetes. The high prevalence of anti-insulin autoantibodies in proinsulin 2 -/-mice indicates that diabetes acceleration relates to altered recognition of proinsulin. The prevalence of anti-glutamic acid decarboxylase autoantibodies and of sialitis is not increased in proinsulin 2 -/-mice. We give evidence that proinsulin 2 expression leads to silencing of T cells specific for an epitope shared by proinsulin 1 and proinsulin 2. In the human, alleles located in the VNTR region flanking the insulin gene control β cell response to glucose and proinsulin expression in the thymus and are key determinants of diabetes susceptibility. Proinsulin 2 -/-NOD mice provide a model to study the role of thymic expression of insulin in susceptibility to diabetes.This article was published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org.

Key Points• BCL-2 homology domain 3 mimetic inhibitor ABT-737 targets leukemia initiating cells and progenitors.• Dephosphorylates RAS signaling proteins and regulates proliferation and differentiation genes detected by gene expression profiling.Myelodysplastic syndrome (MDS) transforms into an acute myelogenous leukemia (AML) with associated increased bone marrow (BM) blast infiltration. Using a transgenic mouse model, MRP8[NRASD12/hBCL-2], in which the NRAS:BCL-2 complex at the mitochondria induces MDS progressing to AML with dysplastic features, we studied the therapeutic potential of a BCL-2 homology domain 3 mimetic inhibitor, ABT-737. Treatment significantly extended lifespan, increased survival of lethally irradiated secondary recipients transplanted with cells from treated mice compared with cells from untreated mice, with a reduction of BM blasts, Lin-/Sca-1 1 /c-Kit 1 , and progenitor populations by increased apoptosis of infiltrating blasts of diseased mice assessed in vivo by technicium-labeled annexin V single photon emission computed tomography and ex vivo by annexin V/7-amino actinomycin D flow cytometry, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling, caspase 3 cleavage, and re-localization of the NRAS:BCL-2 complex from mitochondria to plasma membrane. Phosphoprotein analysis showed restoration of wild-type (WT) AKT or protein kinase B, extracellular signal-regulated kinase 1/2 and mitogen-activated protein kinase patterns in spleen cells after treatment, which showed reduced mitochondrial membrane potential. Exon specific gene expression profiling corroborates the reduction of leukemic cells, with an increase in expression of genes coding for stem cell development and maintenance, myeloid differentiation, and apoptosis. Myelodysplastic features persist underscoring targeting of BCL-2-mediated effects on MDS-AML transformation and survival of leukemic cells. (Blood. 2013; 122(16):2864-2876

IntroductionDespite improved molecular characterization of malignancies and development of targeted therapies, 1 acute leukemia is not curable and few patients survive more than 10 years after diagnosis. 2,3 To further improve outcome, we studied the potential efficacy of boosting the patient's immune response. Therapeutic vaccination aimed at promoting T-cell immunity requires: activation of the innate system, optimal presentation of major histocompatibility complex (MHC) class I-binding peptides, and provision of CD4 ϩ T-cell help. DNA vaccines have the potential to supply all of these. In an animal model of acute promyelocytic leukemia (APL), 4 we developed a promyelocytic leukemia-RAR␣ (PML/RAR␣)-targeted DNA-based vaccine 5 and show that DNA combined with all-trans retinoic acid (ATRA) has a pronounced survival advantage, concomitant with time-dependent antibody production, 5,6 and an increase in interferon-␥ (IFN-␥). 5 A similar approach confirmed these findings. 7 The role of ATRA as an immunomodulator is well documented. [8][9][10][11] Westervelt et al 12 show that ATRA responses are influenced by the presence of an intact adaptive immune response.The present study is aimed at investigating the immune responses involved in the antileukemic effect of the combined ATRA ϩ DNA therapy, particularly those mediated by CD4 ϩ and CD8 ϩ T cells. MethodsWe extended our previous study using the same protocol illustrated in supplemental Figure 1A (available on the Blood website; see the Supplemental Materials link at the top of the online article) where we combined ATRA (5 mg) and a PML-RAR␣FrC DNA construct in an APL mouse model. 5 Peripheral blood (PB) was collected approximately every 20 days from day 19 after APL engraftment to follow the mice clinically. At specific days, mice were killed to evaluate responses. Methods are detailed in the figure legends. Animal studies were undertaken according to the guidelines of the institutional animal care committee of Hôpital Saint-Louis. Results and discussion DNA vaccination combined with ATRA induces long-term survivalOur finding of ATRA ϩ DNA treatment significantly extending survival compared with ATRA alone was confirmed in additional protocols (Figure 1A-B; supplemental Figure 1B-C). We have previously reported that DNA alone elicited a modest survival advantage 5 and that FrC alone failed to give long-term survival 13 (supplemental Figure 1D).ATRA ϩ DNA-treated mice had increased white blood cell counts on day 21 after leukemia engraftment, possibly resulting from the For personal use only. on May 11, 2018. by guest www.bloodjournal.org From increases in CD4 ϩ and CD8 ϩ cells (supplemental Figure 2A). ATRAand nearly half of the ATRA ϩ DNA-treated mice had reduced platelets by day 60 (supplemental Figure 2A). Long-term survivors (LTSs) from the ATRA ϩ DNA-treated group (Ͼ 120 days) had significantly reduced bone marrow blast counts (2%-12%; supplemental Figure 2B). ATRA-alone-treated mice died by day 90.PB absolute counts of CD3 ϩ CD4 ϩ and CD3 ϩ CD8 ϩ subsets, as...

Deciphering mechanisms involved in failure of self tolerance to preproinsulin-2 is a key issue in type 1 diabetes. We used nonautoimmune 129SV/Pas mice lacking preproinsulin-2 to study the immune response to preproinsulin-2. In these mice, a T cell response was detected after immunization with several preproinsulin-2 peptides and confirmed by generating hybridomas. Activation of some of these hybridomas by wild-type (wt) islet cells or recombinant murine proinsulin-2 demonstrated that two epitopes can be generated from the naturally expressed protein. Although T cells from wt mice responded to preproinsulin-2 peptides, we could not detect a response to the naturally processed epitopes in these mice. Moreover, after immunization with recombinant whole proinsulin-2, a T cell response was detected in preproinsulin-2-deficient but not in wt mice. This suggests that islet preproinsulin-2-autoreactive T cells are functionally eliminated in wt mice. We used a transplantation model to evaluate the relevance of reactivity to preproinsulin-2 in vivo. Wild-type preproinsulin-2-expressing islets transplanted in preproinsulin-2-deficient mice elicited a mononuclear cell infiltration and insulin Abs. Graft infiltration was further increased by immunization with preproinsulin-2 peptides. Preproinsulin-2 expression thus shapes the immune response and prevents self reactivity to the islet. Moreover, islet preproinsulin-2 primes an immune response to preproinsulin-2 in deficient mice.

Despite the high incidence of epilepsy in very young children, the availability of approved antiepileptic drugs for this population is limited. This study assessed the efficacy and tolerability of levetiracetam in children younger than 2 years of age with various types of epilepsy. A single-center, retrospective chart review of 28 patients ranging in age from 2 weeks to 22 months treated with levetiracetam over a 2.5-year period was conducted. The mean dosage of levetiracetam was 39 mg/kg per day, and the mean duration of treatment was 6.3 months. The majority of patients (54%) were also taking 1 or 2 other antiepileptic drugs. A reduction in seizure frequency was found in 54%, with 14% achieving seizure freedom. Eight patients showed no response to levetiracetam treatment. Efficacy was highest among patients with generalized epilepsy. Adverse effects occurred in 2 patients and were behavioral in nature. Levetiracetam treatment was safe and effective in this group of very young patients with various types of epilepsy.

The expression of major histocompatibility complex (MHC) class II antigens is constitutive in professional antigen presenting cells (APCs) but can also be induced by interferon-gamma (IFN-g) on the majority of the non professional APCs (e.g. ®broblasts). We have recently characterised a new factor called IK which is an e cient inhibitor of IFN-g induction of MHC class II antigens expression. Here, we demonstrate a novel role for IK in MHC class II expression since over-expression of this protein by stable transfection into human B cells led to a total disappearance of constitutive MHC class II mRNA expression. The class II transactivator (CIITA) is necessary for both constitutive and IFN-g induced MHC class II expressions. Examination of CIITA mRNA in IK stably transfected clones revealed a marked reduction of CIITA mRNA transcription. Taken together these results demonstrate that the IK protein plays a key role in the constitutive expression of MHC class II antigens and that inhibition induced by IK is upstream of CIITA in this regulatory pathway.

In this study, we have investigated the expression of the alpha and beta chains of the IL-2 receptor (IL-2R alpha, IL-2R beta) both at the membrane and at transcriptional levels during the lifespan of human embryonic fibroblasts. Here we show that the mAbs IOT14 and MIK beta 1 directed against the IL-2 binding sites of the IL-2R alpha and IL-2R beta respectively, stain human embryonic fibroblasts early in their life span. Data from [125I]rIL2 cross-linking experiments show the simultaneous expression of two IL-2 binding peptides of 70 and 55 kDa respectively on embryonic young fibroblasts as on lymphoid activated cells. The p55 and the p70 IL-2 binding peptides are shown to be specific for the IL-2R alpha and to the IL-2R beta by the finding that these bands are abolished by excess amounts of cold IL-2 and mAbs directed against the IL-2 binding sites of the alpha and beta chains. Scatchard analysis after [125I]IL-2 labelling shows the presence of both high affinity (150 sites with a Kd of 147 pM) and low affinity (1100 sites with a Kd of 4 nM) IL-2 binding sites. Northern blot and dot blot analysis show the presence of specific transcripts for the IL-2R alpha and IL-2R beta genes in early passaged fibroblasts. By contrast, in senescent cultures, only the IL-2R beta transcript were detected. Finally, IL-2 at low concentrations (36 pM) down modulates the level of the intercellular adhesion molecule ICAM-1 in young but not in senescent cultures.(ABSTRACT TRUNCATED AT 250 WORDS)