[Show abstract][Hide abstract] ABSTRACT: The renin–angiotensin system (RAS), bone morphogenetic protein (BMP), and WNT pathways are involved in pathogenesis of diabetic kidney disease (DKD). This study characterized assays for urinary angiotensinogen (AGT), gremlin-1, and matrix metalloproteinase 7 (MMP-7), components of the RAS, BMP, and WNT pathways and examined their excretion in DKD. We measured urine AGT, gremlin-1, and MMP-7 in individuals with type 1 diabetes and prevalent DKD (n = 20) or longstanding (n = 61) or new-onset (n = 10) type 1 diabetes without DKD. These urine proteins were also quantified in type 2 DKD (n = 11) before and after treatment with candesartan. The utilized immunoassays had comparable inter- and intra-assay and intraindividual variation to assays used for urine albumin. Median (IQR) urine AGT concentrations were 226.0 (82.1, 550.3) and 13.0 (7.8, 20.0) μg/g creatinine in type 1 diabetes with and without DKD, respectively (P < 0.001). Median (IQR) urine gremlin-1 concentrations were 48.6 (14.2, 254.1) and 3.6 (1.7, 5.5) μg/g, respectively (P < 0.001). Median (IQR) urine MMP-7 concentrations were 6.0 (3.8, 10.5) and 1.0 (0.4, 2.9) μg/g creatinine, respectively (P < 0.001). Treatment with candesartan was associated with a reduction in median (IQR) urine AGT/creatinine from 23.5 (1.6, 105.1) to 2.0 (1.4, 13.7) μg/g, which did not reach statistical significance. Urine gremlin-1 and MMP-7 excretion did not decrease with candesartan. In conclusion, DKD is characterized by markedly elevated urine AGT, MMP-7, and gremlin-1. AGT decreased in response to RAS inhibition, suggesting that this marker reflects therapeutic response. Urinary components of the RAS, BMP, and WNT pathways may identify risk of DKD and aid development of novel therapeutics.
[Show abstract][Hide abstract] ABSTRACT: Post-translational modification of self-proteins has been shown to elicit clinically relevant immune responses in rheumatoid arthritis and celiac disease. Accumulating evidence suggests that recognition of modified self-proteins may also be important in type 1 diabetes. Our objective was to identify post-translationally modified GAD65 peptides which are recognized by subjects with type 1 diabetes and to assess their disease relevance. We show that citrullination and transglutamination of peptides can enhance their binding to DRB1*04:01, a diabetes susceptible HLA allele. These and corresponding modifications to amino acids at T cell contact positions modulated the recognition of multiple GAD65 peptides by self-reactive T cells. Using class II tetramers, we verified that memory T cells specific for these modified epitopes were detectable directly ex vivo in the peripheral blood of subjects with type 1 diabetes at significantly higher frequencies than healthy controls. Furthermore, T cells that recognize these modified epitopes were either less responsive or non-responsive to their unmodified counterparts. Our findings suggest that post-translational modification contributes to the progression of autoimmune diabetes by eliciting T cell responses to new epitope specificities that are present primarily in the periphery, thereby circumventing tolerance mechanisms.
[Show abstract][Hide abstract] ABSTRACT: Connecting peptide, or C-peptide, is a protein that joins insulin's α and B chains in the proinsulin molecule. During insulin synthesis, C-peptide is cleaved from proinsulin and secreted in an equimolar concentration to insulin from the β cells. Because C-peptide experiences little first-pass clearance by the liver, and because levels are not affected by exogenous insulin administration, it may be used as a marker of endogenous insulin production and a reflection of β-cell function. Residual β-cell function, as measured by C-peptide in those with type 1 diabetes (T1D), has repeatedly been demonstrated to be clinically important. The Eisenbarth model of type 1 diabetes postulated immune-mediated linear loss of β cells, with clinical diagnosis occurring when there was insufficient insulin secretion to meet glycemic demand. Moreover, the model also implied that all individuals with T1D rapidly and inevitably progressed to absolute insulin deficiency. Correspondingly, it was assumed that most people with longstanding T1D would show little to no residual C-peptide secretion. While more than a quarter century of data confirms that this model remains largely true and appropriately serves as the basis for prevention studies, accumulating evidence suggests that the natural history of β-cell function before, during and after diagnosis is more complex. In this review, we discuss the clinical benefits of residual insulin secretion and present recent data about the natural history of insulin secretion in those with, or at risk for T1D.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE
We studied the utility of the Diabetes Prevention Trial-Type 1 Risk Score (DPTRS) for improving the accuracy of type 1 diabetes (T1D) risk classification in TrialNet Natural History Study (TNNHS) participants.RESEARCH DESIGN AND METHODS
The cumulative incidence of T1D was compared between normoglycemic individuals with DPTRS values >7.00 and dysglycemic individuals in the TNNHS (n = 991). The cumulative incidence was compared between individuals with DPTRS values <7.00 and >7.00 among those with dysglycemia and those with multiple autoantibodies in the TNNHS. DPTRS values >7.00 were compared with dysglycemia for characterizing risk in Diabetes Prevention Trial-Type 1 (DPT-1) (n = 670) and TNNHS participants. The reliability of DPTRS values >7.00 was compared with dysglycemia in the TNNHS.RESULTSThe cumulative incidence of T1D for normoglycemic TNNHS participants with DPTRS values >7.00 was comparable to those with dysglycemia. Among those with dysglycemia, the cumulative incidence was much higher (P < 0.001) for those with DPTRS values >7.00 than for those with values <7.00 (3-year risks: 0.16 for <7.00 and 0.46 for >7.00). Dysglycemic individuals in DPT-1 were at much higher risk for T1D than those with dysglycemia in the TNNHS (P < 0.001); there was no significant difference in risk between the studies among those with DPTRS values >7.00. The proportion in the TNNHS reverting from dysglycemia to normoglycemia at the next visit was higher than the proportion reverting from DPTRS values >7.00 to values <7.00 (36 vs. 23%).CONCLUSIONSDPTRS thresholds can improve T1D risk classification accuracy by identifying high-risk normoglycemic and low-risk dysglycemic individuals. The 7.00 DPTRS threshold characterizes risk more consistently between populations and has greater reliability than dysglycemia.
[Show abstract][Hide abstract] ABSTRACT: Complement component C4 (C4) is a highly variable complement pathway gene situated approximately 500kb from DRB1 and DQB1, the genes most strongly associated with many autoimmune diseases. Variations in C4 copy number, length, and isotype create a highly diverse gene cluster, in which insertion of an endogenous retrovirus in the 9(th) intron of C4, termed HERV-K(C4), is a notable component. Here we investigate the relationship between C4 variation/copy number and type 1 diabetes. We find that individuals with type 1 diabetes have significantly fewer copies of HERV-K(C4), and that this effect is not solely due to linkage with known MHC class II susceptibility alleles. We show that HERV-K(C4) is a novel type 1 diabetes marker that accounts for the disease association previously attributed to some key HLA-DQB1 alleles raising the possibility that this retroviral insertion element contributes to functional protection against type 1 diabetes.
[Show abstract][Hide abstract] ABSTRACT: Fate determination for autoreactive T cells relies on a series of avidity-dependent interactions during T cell selection, represented by two general types of signals, one based on antigen expression and density during T cell development, and one based on genes that interpret the avidity of TCR interaction to guide developmental outcome. We used proinsulin-specific HLA class II tetramers to purify and determine transcriptional signatures for autoreactive T cells under differential selection in type 1 diabetes (T1D), in which insulin (INS) genotypes consist of protective and susceptible alleles that regulate the level of proinsulin expression in the thymus. Upregulation of steroid nuclear receptor family 4A (NR4A) and early growth response family genes in proinsulin-specific T cells was observed in individuals with susceptible INS-VNTR genotypes, suggesting a mechanism for avidity-dependent fate determination of the T cell repertoire in T1D. The NR4A genes act as translators of TCR signal strength that guide central and peripheral T cell fate decisions through transcriptional modification. We propose that maintenance of an NR4A-guided program in low avidity autoreactive T cells in T1D reflects their prior developmental experience influenced by proinsulin expression, identifying a pathway permissive for autoimmunity.
PLoS ONE 01/2014; 9(5):e98074. · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective
We previously reported that two years of co-stimulation modulation with abatacept slowed decline of beta-cell function in recent-onset type 1 diabetes mellitus (T1DM). Subsequently, abatacept was discontinued, and subjects followed to determine whether there was persistence of effect.Research Design and Methods
In 112 subjects (ages 6-36) with T1DM, 77 received abatacept and 35 received placebo infusions intravenously for 27 infusions over two years. The primary outcome - baseline-adjusted geometric mean 2-hour area under the curve (AUC) serum C-peptide during a mixed meal tolerance test (MMTT) at two years - showed higher C-peptide with abatacept versus placebo. Subjects were followed an additional year, off treatment, with MMTTs performed at 30 and 36 months.ResultsC-peptide AUC means, adjusted for age and baseline C-peptide, at 36 months were 0.217 (95% CI: 0.168, 0.268) and 0.141 (95% CI: 0.071, 0.215) nmol/L for abatacept and placebo groups, respectively (p=0.046). The C-peptide decline from baseline remained parallel with an estimated 9.5 months' delay with abatacept. Moreover, HbA1c levels remainded lower in the abatacept group than in the placebo group. The slightly lower (non-significant) mean total insulin dose among the abatacept group reported at 2 years was the same as the placebo group by 3 years.Conclusions
Co-stimulation modulation with abatacept slowed decline of beta-cell function and improved HbA1c in recent-onset T1DM. The beneficial effect was sustained for at least one year after cessation of abatacept infusions, or three years from T1DM diagnosis.
[Show abstract][Hide abstract] ABSTRACT: To clarify whether the rate of decline in stimulated C-peptide (SCP) from 2 to 15 months after diagnosis has changed over an interval of 27 yr.
The rate of decline in SCP levels at 1, 2, 3, 6, 9, 12, and 15 months after diagnosis was compared in four paediatric cohorts from Scandinavian and European countries including 446 children with new onset type 1 diabetes (T1D, 1982-2004). Findings were evaluated against 78 children (2004-2009) from the TrialNet studies.
The mean rate of decline [%/month (±SEM)] in SCP for a 10-yr-old child was 7.7%/month (±1.5) in the 1982-1985 Cohort, 6.3%/month (±1.7) in the 1995-1998 Cohort, 7.8%/month (±0.7) in the 1999-2000 Cohort, and 10.7%/month (±0.9) in the latest 2004-2005 Cohort (p = 0.05). Including the TrialNet Cohort with a rate of decline in SCP of 10.0%/month (±0.9) the differences between the cohorts are still significant (p = 0.039). The rate of decline in SCP was negatively associated with age (p < 0.0001), insulin antibodies (IA) (p = 0.003), and glutamic acid decarboxylase-65 (GAD65A) (p = 0.03) initially with no statistically significant effect of body mass index (BMI) Z-score at 3 months. Also, at 3 months the time around partial remission, the effect of age on SCP was significantly greater in children ≤5 yr compared with older children (p ≤ 0.0001).
During the past 27 yr, initial C-peptide as well as the rate of C-peptide decline seem to have increased. The rate of decline was affected significantly by age, GAD65A, and IA, but not BMI Z-score or initial C-peptide.
[Show abstract][Hide abstract] ABSTRACT: Objective
We previously reported that selective depletion of B-lymphocytes with rituximab, an anti-CD20 monoclonal antibody, slowed decline of beta-cell function in recent-onset type 1 diabetes mellitus (T1DM) at one year. Subjects were followed further to determine whether there was persistence of effect.Research Design and Methods
Eighty-seven subjects (ages 8-40) were randomly assigned to, and 81 received, infusions of rituximab or placebo on days 1, 8, 15, and 22. The primary outcome - baseline-adjusted mean 2-hour area under the curve (AUC) serum C-peptide during a mixed meal tolerance test (MMTT) at one year - showed higher C-peptide AUC with rituximab versus placebo. Subjects were further followed with additional MMTTs every 6 months.ResultsThe rate of decline of C-peptide was parallel between groups, but shifted by 8.2 months in rituximab treated subjects. Over 30 months, AUC, insulin dose, and HbA1c were similar for rituximab and placebo. However, in evaluating change in C-peptide over the entire follow-up period, the rituximab group means were significantly larger as compared within assessment times to the placebo group means using a global test (p = 0.03). Odds ratio for loss of C-peptide to < 0.2 nmol/L following rituximab was 0.565 (p= 0.064). B-lymphocytes recovered to baseline values by 18 months. Serum IgG levels were maintained in the normal range but IgM levels were depressed.Conclusions
Like several other immunotherapeutic approaches tested, in recent-onset T1DM, rituximab delays the fall in C-peptide, but does not appear to fundamentally alter the underlying pathophysiology of the disease.
[Show abstract][Hide abstract] ABSTRACT: We studied the change in the first-phase insulin response (FPIR) during the progression to type 1 diabetes (T1D). Seventy-four oral insulin trial progressors to T1D of the Diabetes Prevention Trial-Type 1 with at least one FPIR measurement after baseline and before diagnosis were studied. The FPIR was examined longitudinally in 26 progressors who had FPIR measurements during each of the 3 years before diagnosis. The association between the change from the baseline FPIR to the last FPIR and time to diagnosis was studied in the remainder (n=48). The 74 progressors had lower baseline FPIR values than non-progressors (n=270) with adjustments for age and BMI. In the longitudinal analysis of the 26 progressors, there was a greater decline in the FPIR from 1.5 to 0.5 years before diagnosis than from 2.5 to 1.5 years before diagnosis. This accelerated decline was also evident in a regression analysis of the 48 remaining progressors in whom the rate of decline became more marked with the approaching diagnosis. The patterns of decline were similar between the longitudinal and regression analyses. There is an acceleration of decline in the FPIR during the progression to T1D which becomes especially marked between 1.5 and 0.5 years before diagnosis.
[Show abstract][Hide abstract] ABSTRACT: Trials of immune therapies in new-onset type 1 diabetes (T1D) have shown success but not all subjects respond and the response duration is limited. Our aim was to determine whether two courses of FcR-nonbinding anti-CD3 mAb, teplizumab, reduces the decline in C-peptide in patients with new-onset T1D two years after disease onset, and we also set out to identify characteristics of responders. We treated 52 subjects with new-onset T1D with teplizumab for 2 weeks at diagnosis and after 1 year in a randomized, open-labeled, controlled trial. In the intention to treat analysis of the primary endpoint, teplizumab-treated patients had a reduced decline in C-peptide at 2 years ((mean, 95% CI) -0.28(-0.36, -0.20) nmol/L) vs. control (-0.46(-0.57, -0.35) nmol/L; p=0.002), a 75% improvement. The most common adverse events were rash, transient upper respiratory infections, headache, and nausea. In a post-hoc analysis, we characterized clinical responders and found that metabolic (HbA1c and insulin use) and immunologic features distinguished this group from non-responders to teplizumab. We conclude that teplizumab treatment preserves insulin production and reduces the use of exogenous insulin in some patients with new-onset T1D. Metabolic and immunologic features at entry can identify a subgroup with robust responses to immune therapy.
[Show abstract][Hide abstract] ABSTRACT: Abstract Background: Most current model-based approaches to closed-loop artificial pancreas systems rely on mathematical equations describing the human glucoregulatory system; however, incorporating the various physiological parameters (e.g., illness, stress) into these models has been problematic. We evaluated a fully automated "fuzzy logic" (FL) closed-loop insulin dosing controller that does not require differential equations of the glucoregulatory system and allows clinicians to personalize dosing aggressiveness to meet individual patient requirements. Subjects and Methods: This pilot study evaluated the FL controller in the setting of bed rest in a very controlled environment. Two carbohydrate-controlled meals were given (30 g at 8 a.m. and 60 g at 2 p.m. without meal announcement or premeal bolus. The primary end point of the study was avoidance of hypoglycemia, defined at <60 mg/dL. Multiple end points related to the frequency and severity of hyperglycemia and hypoglycemia were also assessed. Results: Of the 12 subjects we recruited, 10 were enrolled, and seven completed the study. Two of the enrolled subjects were discontinued because of hypoglycemia; the other was discontinued because of sensor failure. Seven of the 10 subjects who completed the study had average blood glucose values of 165 mg/dL and were within a specified target blood glucose range (70-200 mg/dL) for 76% of the 24-h study period. Conclusions: Our findings suggest that the FL controller provides a viable alternative to model-based controllers as a component of a closed-loop insulin delivery system. Furthermore, our FL controller allows clinicians to easily specify the level of glucose control based on each patient's clinical needs.
[Show abstract][Hide abstract] ABSTRACT: Aims:Our study aims were to determine the frequency of MODY mutations (HNF1A, HNF4A, Glucokinase) in a diverse population of youth with diabetes and to assess how well clinical features identify youth with MODY.Methods:The SEARCH for Diabetes in Youth study is a US multicenter, population-based study of youth with diabetes diagnosed at <20 years. We sequenced genomic DNA for mutations in the HNF1A, HNF4A, and glucokinase genes in 586 participants enrolled in SEARCH between 2001 and 2006. Selection criteria included diabetes autoantibody negativity and fasting C-peptide levels ≥0.8 ng/ml.Results:We identified a mutation in one of three MODY genes in 47 participants, or 8.0% of the tested sample, for a prevalence of at least 1.2% in the pediatric diabetes population. Of these, only three had a clinical diagnosis of MODY, and the majority was treated with insulin. Compared with the MODY-negative group, MODY-positive participants had lower FCP levels (2.2±1.4 ng/ml vs. 3.2±2.1 ng/ml, p<0.01) and fewer type 2 diabetes-like metabolic features. Parental history of diabetes did not significantly differ between the two groups.Conclusions/Interpretation:In this systematic study of MODY in a large pediatric US diabetes cohort, unselected by referral pattern or family history, MODY was usually misdiagnosed and incorrectly treated with insulin. While many type 2 diabetes-like metabolic features were less common in the mutation-positive group, no single characteristic identified all patients with mutations. Clinicians should be alert to the possibility of MODY diagnosis, particularly in antibody negative youth with diabetes.
The Journal of clinical endocrinology and metabolism 06/2013; · 6.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: CD4(+) memory cell development is dependent upon T cell receptor (TCR) signal strength, antigen dose and the cytokine milieu, all of which are altered in type 1 diabetes (T1D). We hypothesized that CD4(+) T cell turnover would be greater in type 1 diabetes subjects compared to controls. In vitro studies of T cell function are unable to evaluate dynamic aspects of immune cell homoeostasis. Therefore, we used deuterium oxide ((2) H2 O) to assess in vivo turnover of CD4(+) T cell subsets in T1D (n = 10) and control subjects (n = 10). Serial samples of naive, memory and regulatory (Treg ) CD4(+) T cell subsets were collected and enrichment of deoxyribose was determined by gas chromatography-mass spectrometry (GC-MS). Quantification of T cell turnover was performed using mathematical models to estimate fractional enrichment (f, n = 20), turnover rate (k, n = 20), proliferation (p, n = 10) and disappearance (d*, n = 10). Although turnover of Tregs was greater than memory and naive cells in both controls and T1D subjects, no differences were seen between T1D and controls in Treg or naive kinetics. However, turnover of CD4(+) memory T cells was faster in those with T1D compared to control subjects. Measurement and modelling of incorporated deuterium is useful for evaluating the in vivo kinetics of immune cells in T1D and could be incorporated into studies of the natural history of disease or clinical trials designed to alter the disease course. The enhanced CD4(+) memory T cell turnover in T1D may be important in understanding the pathophysiology and potential treatments of autoimmune diabetes.
[Show abstract][Hide abstract] ABSTRACT: Abstract We explored the influence of exposure to maternal diabetes in utero on β cell decline measured by fasting C-peptide (FCP) among 1079 youth <20 years with diabetes, including 941 with type 1 and 138 with type 2 diabetes. Youths exposed to maternal diabetes had FCP levels that were 17% lower among youth with type 2 diabetes [95% confidence interval (CI): -34%, +6%] and 15% higher among youth with type 1 diabetes (95%CI: -14%, +55%) than their unexposed counterparts, although differences were not statistically significant (p=0.13 and p=0.35, respectively). Exposure to maternal diabetes was not associated with FCP decline in youth with type 2 (p=0.16) or type 1 diabetes (p=0.90); nor was the effect of in utero exposure on FCP modified by diabetes type. Findings suggest that exposure to maternal diabetes in utero may not be an important determinant of short-term β-cell function decline in youth with type 1 or type 2 diabetes.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Innate immunity contributes to the pathogenesis of autoimmune diseases, such as type 1 diabetes, but until now no randomised, controlled trials of blockade of the key innate immune mediator interleukin-1 have been done. We aimed to assess whether canakinumab, a human monoclonal anti-interleukin-1 antibody, or anakinra, a human interleukin-1 receptor antagonist, improved β-cell function in recent-onset type 1 diabetes. METHODS: We did two randomised, placebo-controlled trials in two groups of patients with recent-onset type 1 diabetes and mixed-meal-tolerance-test-stimulated C peptide of at least 0·2 nM. Patients in the canakinumab trial were aged 6-45 years and those in the anakinra trial were aged 18-35 years. Patients in the canakinumab trial were enrolled at 12 sites in the USA and Canada and those in the anakinra trial were enrolled at 14 sites across Europe. Participants were randomly assigned by computer-generated blocked randomisation to subcutaneous injection of either 2 mg/kg (maximum 300 mg) canakinumab or placebo monthly for 12 months or 100 mg anakinra or placebo daily for 9 months. Participants and carers were masked to treatment assignment. The primary endpoint was baseline-adjusted 2-h area under curve C-peptide response to the mixed meal tolerance test at 12 months (canakinumab trial) and 9 months (anakinra trial). Analyses were by intention to treat. These studies are registered with ClinicalTrials.gov, numbers NCT00947427 and NCT00711503, and EudraCT number 2007-007146-34. FINDINGS: Patients were enrolled in the canakinumab trial between Nov 12, 2010, and April 11, 2011, and in the anakinra trial between Jan 26, 2009, and May 25, 2011. 69 patients were randomly assigned to canakinumab (n=47) or placebo (n=22) monthly for 12 months and 69 were randomly assigned to anakinra (n=35) or placebo (n=34) daily for 9 months. No interim analyses were done. 45 canakinumab-treated and 21 placebo-treated patients in the canakinumab trial and 25 anakinra-treated and 26 placebo-treated patients in the anakinra trial were included in the primary analyses. The difference in C peptide area under curve between the canakinumab and placebo groups at 12 months was 0·01 nmol/L (95% CI -0·11 to 0·14; p=0·86), and between the anakinra and the placebo groups at 9 months was 0·02 nmol/L (-0·09 to 0·15; p=0·71). The number and severity of adverse events did not differ between groups in the canakinumab trial. In the anakinra trial, patients in the anakinra group had significantly higher grades of adverse events than the placebo group (p=0·018), which was mainly because of a higher number of injection site reactions in the anakinra group. INTERPRETATION: Canakinumab and anakinra were safe but were not effective as single immunomodulatory drugs in recent-onset type 1 diabetes. Interleukin-1 blockade might be more effective in combination with treatments that target adaptive immunity in organ-specific autoimmune disorders. FUNDING: National Institutes of Health and Juvenile Diabetes Research Foundation.
[Show abstract][Hide abstract] ABSTRACT: IL-2 facilitates immunity or tolerance depending on its availability. In model systems, it is well established that low dose IL-2 promotes selective expansion of regulatory T cells (Treg), an IL-2 responsive cell type known to control autoimmunity. Moreover, many autoimmune diseases are marked by defects in Treg and/or IL-2/IL-2 receptor signaling. Thus, patients with immune-mediated diseases were treated with IL-2 with the goal of increasing Treg and controlling autoimmunity. In graft versus host disease, HCV-induced vasculitis and type 1 diabetes (T1D), Treg numbers increased with IL-2 therapy. Yet there was no relationship between Treg number and clinical outcome. In fact, in T1D subjects treated with rapamycin and IL-2 therapy there was no measureable clinical benefit. In this review, we compare results from IL-2 treatment of patients with immune-mediated diseases, discuss possible mechanisms of IL-2 treatment and suggest future directions for use of IL-2 therapy in T1D.
[Show abstract][Hide abstract] ABSTRACT: IL-2 receptor (IL-2R) signaling is essential for optimal stability and function of CD4(+)CD25(hi)FOXP3(+) regulatory T cells (Treg); a cell type that plays an integral role in maintaining tolerance. Thus, we hypothesized that decreased response to IL-2 may be a common phenotype of subjects who have autoimmune diseases associated with variants in the IL2RA locus, including T1D and MS, particularly in cells expressing the high affinity IL-2R alpha chain (IL-2RA or CD25). To examine this question we used phosphorylation of STAT5 (pSTAT5) as a downstream measure of IL-2R signaling, and found a decreased response to IL-2 in CD4(+)CD25(hi) T cells of T1D and MS, but not SLE patients. Since the IL2RArs2104286 haplotype is associated with T1D and MS, we measured pSTAT5 in controls carrying the rs2104286 risk haplotype to test whether this variant contributed to reduced IL-2 responsiveness. Consistent with this, we found decreased pSTAT5 in subjects carrying the rs2104286 risk haplotype. Reduced IL-2R signaling did not result from lower CD25 expression on CD25(hi) cells; instead we detected increased CD25 expression on naive Treg from controls carrying the rs2104286 risk haplotype, and subjects with T1D and MS. However the rs2104286 risk haplotype correlated with increased soluble IL-2RA levels, suggesting that shedding of the IL-2R may account in part for the reduced IL-2R signaling associated with the rs2104286 risk haplotype. In addition to risk variants in IL2RA, we found that the T1D-associated risk variant of PTPN2rs1893217 independently contributed to diminished IL-2R signaling. However, even when holding genotype constant at IL2RA and PTPN2, we still observed a significant signaling defect in T1D and MS patients. Together, these data suggest that multiple mechanisms converge in disease leading to decreased response to IL-2, a phenotype that may eventually lead to loss of tolerance and autoimmunity.
PLoS ONE 01/2013; 8(12):e83811. · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Type 1 diabetes results from autoimmune targeting of the pancreatic β cells, likely mediated by effector memory T (Tem) cells. CD2, a T cell surface protein highly expressed on Tem cells, is targeted by the fusion protein alefacept, depleting Tem cells and central memory T (Tcm) cells. We postulated that alefacept would arrest autoimmunity and preserve residual β cells in patients newly diagnosed with type 1 diabetes.
The T1DAL study is a phase 2, double-blind, placebo-controlled trial in patients with type 1 diabetes, aged 12–35 years who, within 100 days of diagnosis, were enrolled at 14 US sites. Patients were randomly assigned (2:1) to receive alefacept (two 12-week courses of 15 mg intramuscularly per week, separated by a 12-week pause) or a placebo. Randomisation was stratified by site, and was computer-generated with permuted blocks of three patients per block. All participants and site personnel were masked to treatment assignment. The primary endpoint was the change from baseline in mean 2 h C-peptide area under the curve (AUC) at 12 months. Secondary endpoints at 12 months were the change from baseline in the 4 h C-peptide AUC, insulin use, major hypoglycaemic events, and HbA1c concentrations. This trial is registered with ClinicalTrials.gov, number NCT00965458.
Of 73 patients assessed for eligibility, 33 were randomly assigned to receive alefacept and 16 to receive placebo. The mean 2 h C-peptide AUC at 12 months increased by 0·015 nmol/L (95% CI −0·080 to 0·110) in the alefacept group and decreased by 0·115 nmol/L (–0·278 to 0·047) in the placebo group, and the difference between groups was not significant (p=0·065). However, key secondary endpoints were met: the mean 4 h C-peptide AUC was significantly higher (mean increase of 0·015 nmol/L [95% CI −0·076 to 0·106] vs decrease of −0·156 nmol/L [–0·305 to −0·006]; p=0·019), and daily insulin use (0·48 units per kg per day for placebo vs 0·36 units per kg per day for alefacept; p=0·02) and the rate of hypoglycaemic events (mean of 10·9 events per person per year for alefacept vs 17·3 events for placebo; p<0·0001) was significantly lower at 12 months in the alefacept group than in the placebo group. Mean HbA1c concentrations at week 52 were not different between treatment groups (p=0·75). So far, no serious adverse events were reported and all patients had at least one adverse event. In the alefacept group, 29 (88%) participants had an adverse event related to study drug versus 15 (94%) participants in the placebo group. In the alefacept group, 14 (42%) participants had grade 3 or 4 adverse events compared with nine (56%) participants in the placebo group; no deaths occurred.
Although the primary outcome was not met, at 12 months, alefacept preserved the 4 h C-peptide AUC, lowered insulin use, and reduced hypoglycaemic events, suggesting efficacy. Safety and tolerability were similar in the alefacept and placebo groups. Alefacept could be useful to preserve β-cell function in patients with new-onset type 1 diabetes.
US National Institutes of Health and the Juvenile Diabetes Research Foundation.
The Lancet Diabetes & Endocrinology. 01/2013; 1(4):284–294.