BackgroundInterleukin-2 (IL-2) has an essential role in the expansion and function of CD4+ regulatory T cells (Tregs). Tregs reduce tissue damage by limiting the immune response following infection and regulate autoreactive CD4+ effector T cells (Teffs) to prevent autoimmune diseases, such as type 1 diabetes (T1D). Genetic susceptibility to T1D causes alterations in the IL-2 pathway, a finding that supports Tregs as a cellular therapeutic target. Aldesleukin (Proleukin; recombinant human IL-2), which is administered at high doses to activate the immune system in cancer immunotherapy, is now being repositioned to treat inflammatory and autoimmune disorders at lower doses by targeting Tregs.Methods and FindingsTo define the aldesleukin dose response for Tregs and to find doses that increase Tregs physiologically for treatment of T1D, a statistical and systematic approach was taken by analysing the pharmacokinetics and pharmacodynamics of single doses of subcutaneous aldesleukin in the Adaptive Study of IL-2 Dose on Regulatory T Cells in Type 1 Diabetes (DILT1D), a single centre, non-randomised, open label, adaptive dose-finding trial with 40 adult participants with recently diagnosed T1D. The primary endpoint was the maximum percentage increase in Tregs (defined as CD3+CD4+CD25highCD127low) from the baseline frequency in each participant measured over the 7 d following treatment. There was an initial learning phase with five pairs of participants, each pair receiving one of five pre-assigned single doses from 0.04 × 106 to 1.5 × 106 IU/m2, in order to model the dose-response curve. Results from each participant were then incorporated into interim statistical modelling to target the two doses most likely to induce 10% and 20% increases in Treg frequencies. Primary analysis of the evaluable population (n = 39) found that the optimal doses of aldesleukin to induce 10% and 20% increases in Tregs were 0.101 × 106 IU/m2 (standard error [SE] = 0.078, 95% CI = −0.052, 0.254) and 0.497 × 106 IU/m2 (SE = 0.092, 95% CI = 0.316, 0.678), respectively. On analysis of secondary outcomes, using a highly sensitive IL-2 assay, the observed plasma concentrations of the drug at 90 min exceeded the hypothetical Treg-specific therapeutic window determined in vitro (0.015–0.24 IU/ml), even at the lowest doses (0.040 × 106 and 0.045 × 106 IU/m2) administered. A rapid decrease in Treg frequency in the circulation was observed at 90 min and at day 1, which was dose dependent (mean decrease 11.6%, SE = 2.3%, range 10.0%–48.2%, n = 37), rebounding at day 2 and increasing to frequencies above baseline over 7 d. Teffs, natural killer cells, and eosinophils also responded, with their frequencies rapidly and dose-dependently decreased in the blood, then returning to, or exceeding, pretreatment levels. Furthermore, there was a dose-dependent down modulation of one of the two signalling subunits of the IL-2 receptor, the β chain (CD122) (mean decrease = 58.0%, SE = 2.8%, range 9.8%–85.5%, n = 33), on Tregs and a reduction in their sensitivity to al...

Aims/hypothesis Type 1 diabetes results from a chronic autoimmune process continuing for years after presentation. We tested whether treatment with teplizumab (a Fc receptor non-binding anti-CD3 monoclonal antibody), after the new-onset period, affects the decline in C-peptide production in individuals with type 1 diabetes. Methods In a randomised placebo-controlled trial we treated 58 participants with type 1 diabetes for 4–12 months with teplizumab or placebo at four academic centres in the USA. A central randomisation centre used computer generated tables to allocate treatments. Investigators, patients, and caregivers were blinded to group assignment. The primary outcome was a comparison of C-peptide responses to a mixed meal after 1 year. We explored modification of treatment effects in subgroups of patients. Results Thirty-four and 29 subjects were randomized to the drug and placebo treated groups, respectively. Thirty-one and 27, respectively, were analysed. Although the primary outcome analysis showed a 21.7% higher C-peptide response in the teplizumab-treated group (0.45 vs 0.371; difference, 0.059 [95% CI 0.006, 0.115] nmol/l) (p=0.03), when corrected for baseline imbalances in HbA1c levels, the C-peptide levels in the teplizumab-treated group were 17.7% higher (0.44 vs 0.378; difference, 0.049 [95% CI 0, 0.108] nmol/l, p=0.09). A greater proportion of placebo-treated participants lost detectable C-peptide responses at 12 months (p=0.03). The teplizumab group required less exogenous insulin (p<0.001) but treatment differences in HbA1c levels were not observed. Teplizumab was well tolerated. A subgroup analysis showed that treatment benefits were larger in younger individuals and those with HgbA1c <6.5% at entry. Clinical responders to teplizumab had an increase in circulating CD8 central memory cells 2 months after enrolment compared with non-responders. Conclusions/interpretations This study suggests that deterioration in insulin secretion may be affected by immune therapy with teplizumab after the new-onset period but the magnitude of the effect is less than during the new-onset period. Our studies identify characteristics of patients most likely to respond to this immune therapy. Trial registration ClinicalTrials.gov NCT00378508 Funding This work was supported by grants 2007-502, 2007-1059 and 2006-351 from the JDRF and grants R01 DK057846, P30 DK20495, UL1 RR024139, UL1RR025780, UL1 RR024131 and UL1 RR024134 from the NIH.

The development and optimization of immune therapies in patients has been hampered by the lack of preclinical models in which their effects on human immune cells can be studied. As a result, observations that have been made in preclinical studies have suggested mechanisms of drug action in murine models that may not be confirmed in clinical studies. We have utilized a humanized mouse reconstituted with human hematopoetic stem cells to circumvent these limitations. We have studied the effects of teplizumab in this model, a Fc receptor non-binding humanized monoclonal anti-CD3 antibody that has been used to treat patients with Type 1 diabetes mellitus. A novel mechanism of action was identified where human gut tropic CCR6+ T cells leave the circulation and secondary lymph organs and migrate to the small intestine. They become producers of IL-10 which can be detected in the peripheral circulation. Blockade of migration of T cells to the small intestine by natalizumab abolishes the treatment effects of teplizumab. Direct translation of these findings was possible in patients with Type 1 diabetes treated with teplizumab since we found there is increased expression of IL-10 by CD4+CD25highCCR6+FoxP3 cells when they emerge into the peripheral circulation. These findings demonstrate that humanized mice may be used to identify novel immunologic mechanisms that occur in patients treated with immune modulators.

Type 1 diabetes is a common, severe chronic autoimmune disease that is characterized by the progressive and insidious loss of self-tolerance to the insulin-producing pancreatic islet β-cells. This loss of self-tolerance leads to the destruction of β-cells and the development of overt hyperglycaemia at diagnosis. The incidence and prevalence of type 1 diabetes is rapidly increasing worldwide, and this has led to intensive efforts to develop immunotherapies to induce remission of the disease and improve clinical outcomes. Immunotherapy aims to restore self-tolerance, resulting in the downregulation of autoimmune responses to pancreatic self-antigens and arrested ongoing β-cell destruction. When combined with replacement of the lost insulin-producing cells, this may lead to the restoration of euglycaemia. In this review, we discuss the current knowledge of the immunopathogenesis of type 1 diabetes and how this information has been translated into clinical trials. We also discuss next-generation combination immunotherapies that may be administered as adjuvant therapy at time of diagnosis.

The maintenance of peripheral naive T lymphocytes in humans is dependent on their homeostatic division, not continuing emigration from the thymus, which undergoes involution with age. However, postthymic maintenance of naive T cells is still poorly understood. Previously we reported that recent thymic emigrants (RTEs) are contained in CD31+CD25− naive T cells as defined by their levels of signal joint T cell receptor rearrangement excision circles (sjTRECs). Here, by differential gene expression analysis followed by protein expression and functional studies, we define that the naive T cells having divided the least since thymic emigration express complement receptors (CR1 and CR2) known to bind complement C3b- and C3d-decorated microbial products and, following activation, produce IL-8 (CXCL8), a major chemoattractant for neutrophils in bacterial defense. We also observed an IL-8–producing memory T cell subpopulation coexpressing CR1 and CR2 and with a gene expression signature resembling that of RTEs. The functions of CR1 and CR2 on T cells remain to be determined, but we note that CR2 is the receptor for Epstein-Barr virus, which is a cause of T cell lymphomas and a candidate environmental factor in autoimmune disease.

Tumour necrosis factor (TNF) plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA) and it has been shown that the TNF-lymphotoxin (TNF-LT) region influences susceptibility to RA. To investigate the role of the TNF-LT locus further, inheritance of TNF 5' promoter alleles was determined in multiplex RA families. Six previously defined TNF promoter single nucleotide polymorphisms (SNPs) (-238, -308, -376, -857, -863, -1031) were observed in these families and in addition, a heretofore undocumented adenine (A) to cytosine (C) substitution at position -572 relative to the transcription start site was defined. TNF 5' promoter SNPs were found to co-segregate with specific TNF microsatellite haplotypes. In particular, the SNP -308A allele was found to be inherited with the TNF a2, b3, c1, d1, e3 (H2) microsatellite haplotype (P < 0.001) which had previously been found to be associated with RA in individuals heterozygous for the HLA-DR 'shared epitope' (SE). When the data were stratified by the presence of the SE with further stratification according to SE DR subtypes and analysed by transmission disequilibrium test (TDT) for which offspring were assumed independent, the -308A and -857T alleles were found to be associated with RA in patients carrying the SE (P = 0.0076 and 0.0063 respectively). The data were further stratified to analyse for association in individuals homozygous or heterozygous for SE alleles. Results showed that the -308A allele was significantly associated with RA susceptibility in individuals heterozygous for the SE (P < 0.001) with the significance only occurring in patients carrying HLA-DR4 (P < 0.001), while the -857T allele was significant in individuals homozygous for the SE (P = 0.0039). Further analysis using the pedigree disequilibrium test (PDT) which conservatively adjusts for all sources of familial correlation except that conferred by linkage disequilibrium still indicated a significant role for the -308A and -857T alleles. These data provide evidence that TNF promoter SNPs may play an independent role in RA susceptibility in specific immunogenetically-defined groups of RA patients.

BACKGROUND. Type 1 diabetes (T1D) results from loss of immune regulation, leading to the development of autoimmunity to pancreatic β cells, involving autoreactive T effector cells (Teffs). Tregs, which prevent autoimmunity, require IL-2 for maintenance of immunosuppressive functions. Using a response-adaptive design, we aimed to determine the optimal regimen of aldesleukin (recombinant human IL-2) to physiologically enhance Tregs while limiting expansion of Teffs. METHODS. DILfrequency is a nonrandomized, open-label, response-adaptive study of participants, aged 18-70 years, with T1D. The initial learning phase allocated 12 participants to 6 different predefined regimens. Then, 3 cohorts of 8 participants were sequentially allocated dose frequencies, based on repeated interim analyses of all accumulated trial data. The coprimary endpoints were percentage change in Tregs and Teffs and CD25 (α subunit of the IL-2 receptor) expression by Tregs, from baseline to steady state. RESULTS. Thirty-eight participants were enrolled, with thirty-six completing treatment. The optimal regimen to maintain a steady-state increase in Tregs of 30% and CD25 expression of 25% without Teff expansion is 0.26 × 10 6 IU/m 2 (95% CI-0.007 to 0.485) every 3 days. Tregs and CD25 were dose-frequency responsive, Teffs were not. The commonest adverse event was injection site reaction (464 of 694 events). CONCLUSIONS. Using a response-adaptive design, aldesleukin treatment can be optimized. Our methodology can generally be employed to immediately access proof of mechanism, thereby leading to more efficient and safe drug development.

Immune deficient mice, reconstituted with human stem cells, have been used to analyze human immune responses in vivo. Although they have been used to study immune responses to xenografts, allografts, and pathogens, there have not been models of autoimmune disease in which the mechanisms of the pathologic process can be analyzed. We have found that reconstituted “humanized” mice treated with anti-CTLA-4 antibody (ipilimumab) develop autoimmune disease characterized by hepatitis, adrenalitis, sialitis, ANAs, and weight loss. Induction of autoimmunity involved activation of T cells and cytokine production and increased infiltration of antigen presenting cells. When anti-CTLA-4 mAb treated mice were co-treated with anti-CD3 mAb (teplizumab) hepatitis and ANAs were no longer seen and weight loss did not occur. The anti-CD3 blocked proliferation and activation of T cells, release of IFNγ and TNF, macrophage infiltration and release of IP-10 that was induced with anti-CTLA-4 mAb. We also found increased levels of Tregs (CD25+CD127-) in the spleen and mesenteric lymph nodes in the mice treated with both antibodies and greater constitutive phosphorylation of STAT5 in Tregs in spleen cells compared to mice treated with anti-CTLA-4 mAb alone. We describe the first model of human autoimmune disease in vivo. Humanized mice may be useful for understanding the mechanisms of biologics that are used in patients. Hepatitis, lymphadenopathy, and other inflammatory sequelae are side effects of ipilumimab treatment in humans and the present study may provide insights into this pathogenesis and the effects of immunologics on autoimmunity.