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To protect the organism against autoimmunity, self-reactive effector/memory T cells (T E/M ) are controlled by cell-intrinsic and -extrinsic regulatory mechanisms. However, how some T E/M cells escape regulation and cause autoimmune disease is currently not understood. Here we show that blocking IL-7 receptor-α (IL-7Rα) with monoclonal antibodies in nonobese diabetic (NOD) mice prevented autoimmune diabetes and, importantly, reversed disease in new-onset diabetic mice. Surprisingly, IL-7-deprived diabetogenic T E/M cells remained present in the treated animals but showed increased expression of the inhibitory receptor Programmed Death 1 (PD-1) and reduced IFN-γ production. Conversely, IL-7 suppressed PD-1 expression on activated T cells in vitro. Adoptive transfer experiments revealed that T E/M cells from anti-IL-7Rα-treated mice had lost their pathogenic potential, indicating that absence of IL-7 signals induces cell-intrinsic tolerance. In addition to this mechanism, IL-7Rα blockade altered the balance of regulatory T cells and T E/M cells, hence promoting cell-extrinsic regulation and further increasing the threshold for diabetogenic T-cell activation. Our data demonstrate that IL-7 contributes to the pathogenesis of autoimmune diabetes by enabling T E/M cells to remain in a functionally competent state and suggest IL-7Rα blockade as a therapy for established T-cell-dependent autoimmune diseases.type 1 diabetes | cytokines | immune regulation

TEL-AML1 (ETV6-RUNX1) is the most common translocation in the childhood leukemias, and is a prenatal mutation in most children. This translocation has been detected at a high rate among newborns (f1%); therefore, the rate-limiting event for leukemia seems to be secondary mutations. One such frequent mutation in this subtype is partial deletion of chromosome 12p, trans from the translocation. Nine del(12p) breakpoints within six leukemia cases were sequenced to explore the etiology of this genetic event, and most involved cryptic sterile translocations. Twelve of 18 del(12p) parent sequences involved in these breakpoints were located in repeat regions (8 of these in long interspersed nuclear elements). This stands in contrast with TEL-AML1, in which only 21 of 110 previously assessed breakpoints (19%) occur in DNA repeats (P = 0.0001). An exploratory assessment of archived neonatal blood cards revealed significantly more long interspersed nuclear element CpG methylations in individuals at birth who were later diagnosed with TEL-AML1 leukemia, compared with individuals who did not contract leukemia (P = 0.01). Nontemplate nucleotides were also more frequent in del(12p) than in TEL-AML1 junctions (P = 0.004), suggesting formation by terminal deoxynucleotidyl transferase. Assessment of six archived neonatal blood cards indicated that no del(12p) rearrangements backtracked to birth, although two of these patients were previously positive for TEL-AML1 using the same assay with comparable sensitivity. These data are compatible with a two-stage natural history: TEL-AML1 occurs prenatally, and del(12p) occurs postnatally in more mature cells with a structure that suggests the involvement of retrotransposon instability. [Cancer Res 2008;68(23):9935-44]

E2a-Pbx1 is expressed as a result of the t(1;19) chromosomal translocation in nearly 5% of cases of acute lymphoblastic leukemia. The E2a-Pbx1 chimeric transcription factor contains the N-terminal transactivation domain of E2A fused to the C-terminal DNAbinding homeodomain of Pbx1. Previews studies indicate that additional genetic events may be required for E2A-Pbx1-leukemic transformation, based on long incubation times and monoclonal nature of tumors observed in mouse models. While there is no doubt of its oncogenic potential, the mechanisms of E2a-Pbx1-mediated pre-B cell transformation and the nature of direct E2a-Pbx1 target genes and additional events that complement the fusion oncogene to create full-blown leukemia are still unclear. Herein we used chromatin immunoprecipitation (ChIP-chip) assays to identify direct targets of E2a-Pbx1, and we used gene and miRNA expression arrays of siRNA E2a-Pbx1-silenced cells to evaluate changes in expression induced by the fusion protein. To identify complementary genetic rearrangements, analyses of primary E2a-Pbx1 leukemias were performed to copy number changes and loss of heterozygosity which might identify mutations that synergize with the direct/functional E2a-Pbx1 targets to produce the leukemic phenotype. These arrays were analyzed in comparison to high-density gene promoter methylation arrays. Our data identified members of the WNT pathway as direct targets of E2a-Pbx1. Expression data from E2a-Pbx1 silenced cells support this finding as they demonstrate a functional regulation of this pathway. We further show a differential impact of E2a-Pbx1 silencing on the miRNA profile and identify E2a-Pbx1 dependent miRNAs. Using CGH arrays on primary E2a-Pbx1 samples we were able to pinpoint candidate secondary mutations as well as broad genetic categories: cases with 1q+, 1q+ combined with 9p-, and, separately, cases with +8. In summary we present direct and functional E2a-Pbx1 targets as well as candidate secondary mutations. We propose a model were direct and functional E2a- Pbx1 driven pathways that might include both genes and miRNAs might collaborate with identified auxiliary events to produce the E2a-Pbx1 leukemia.

Supplementary Table 1 from Chromosome 12p Deletions in <i>TEL-AML1</i> Childhood Acute Lymphoblastic Leukemia Are Associated with Retrotransposon Elements and Occur Postnatally